A weight gain chart for pregnant women designed in Chile

copy Blackwell Publishing Ltd 2005

Maternal and Child Nutrition

1

pp 77ndash90

77

Blackwell Science LtdOxford UKMCNMaternal and Child Nutrition1740-8695Blackwell Publishing1

2

7790Original Article

Weight gain chart for pregnant women

F Mardones and P Rosso

Correspondence Francisco Mardones Pontificia Universidad

Catoacutelica de Chile Faculty of Medicine Department of Public

Health Marcoleta 434 Santiago Chile Tel 562 354 6898

562 354 3038 fax 562 633 1840 e-mail mardonesmedpuccl

or fmardonspuccl

Original Article

A weight gain chart for pregnant women designed in Chile

Francisco

Mardones

MD MSc

and

Pedro

Rosso

MD

dagger

Pontificia Universidad Catoacutelica de Chile Faculty of Medicine Department of Public Health Marcoleta 434 Santiago Chile and

dagger

Pontificia Universidad Catoacutelica de Chile Faculty of Medicine Alameda 340 Santiago Chile

Abstract

The weight gain chart for pregnant women developed by Rosso and Mardones (RM chart1997) is analysed and compared with other charts in terms of its usefulness for targetingnutritional interventions aimed at preventing low or high birth weights The RM chart definescategories of maternal nutritional status in early gestation based on weightheight expressedeither as percentage of standard weight (PSW) or body mass index (BMI) and desirablegestational weight gains for each of these categories Weight gain recommendations of the RMchart are proportional to maternal height For underweight women the weight recommendationwas derived from actual data while for overweight and obese women it is based on dataextrapolations Since 1987 the Chilean National Health Service has used the RM chart as astandard in prenatal care in all its clinics covering approximately 70 of the countryrsquos popula-tion mostly middle and low income women During the 1987ndash2001 period the proportion ofunderweight pregnant women and infants with birth weight

lt

3000 g decreased significantly andproportionally Nevertheless the proportion of obese pregnant women and infants with birthweight

ge

4000 g increased during this period Multifactorial social changes including a decade ofsubstantial economic growth in the country with improved family income precludes the possi-bility of determining the efficacy of the RM chart in this group However the widespread useof the RM chart indicates that it is a helpful and easy-to-use instrument in the field Furtherby its clear graphical presentation of maternal nutritional status it helps draw the attention ofhealth personnel to women who need special nutritional advice and support

Keywords

weight gain chart pregnancy

Introduction

Both maternal anthropometry and weight gain duringpregnancy are important determinants of birthweight (Institute of Medicine 1990 Rosso 1990) In

78




1

pp 77ndash90

addition given their sensitivity to weight and bodyimage issues women are likely to request adviceabout weight increment during pregnancy (Abrams

et al

2000)In Chile during the 1980s we developed an instru-

ment that classifies mothers according to their nutri-tional status allowing monitoring of adequacy ofweight gain during gestation (Mardones and Rosso1997) This instrument [the Rosso and Mardones(RM) chart] which is a development of a previouschart (Rosso 1985) enables the identification at anygestational age of mothers at risk of delivering eithersmall or large for gestational age babies and setsweight gain goals for each individual mother Thesegoals can then be used by health personnel to monitoradequacy of weight gain and to provide either dieteticcounselling or food supplements The chart can beeasily used in prenatal clinics of developing countriesand is currently used in several Latin Americacountries

In the present paper the usefulness of the RMchart in targeting interventions aimed at preventinglow or high birth weights is analysed and the featureswhich make it particularly useful in field conditionsdiscussed Birth weight of less than 3000 g is used todefine small for gestational age infants Weight-for-gestation charts and tables published by Lubchencoand many subsequent workers are frequentlyadopted to define small for gestational age infantsusually those below the 10th centile at a given gesta-tion (Thomson 1983) The majority of infants diag-nosed as small for gestational age or intrauterinegrowth retarded weigh less than 3000 g cases mostaffected by maternal nutritional status and social con-ditions are those in the 2500ndash2999 category (Pufferand Serrano 1987) A birth weight of

ge

4000 g definesmacrosomic or large for gestational age infants Thisconcurs with other weight-for-gestation charts defin-ing large for gestational age infants as those over the90th centile at a given gestation All infants diagnosedas large for gestational age fall within the birth weightof

ge

4000 g in most texts (Thomson 1983)The above mentioned birth weight categories carry

increased mortality and morbidity risks during thefirst year of life (Institute of Medicine 1990) Furtherthere are other long-term outcomes such as suscepti-

bility to chronic disease in later life lsquoThere is consid-erable evidence mostly from developed countriesthat intrauterine growth retardation is associatedwith an increased risk of coronary heart diseasestroke diabetes and raised blood pressure Large sizeat birth is also associated with an increased risk ofdiabetes and cardiovascular diseasersquo (World HealthOrganization 2003)

We discuss and comment on the joint evolution inChile of maternal anthropometry and birth weightvalues between 1987 and 2001 following the adoptionof the RM chart by the Chilean National Health Ser-vices Many other factors may have influenced thisevolution so it is not possible to identify the specificeffects of the RM chart However observational andexperimental studies are presented as favourable evi-dence for its use

Anthropometry

The anthropometric characteristics of individualsreflect their body mass and the proportion of fat andlean tissue Body weight and the proportion of fat orlean tissue are determined by the individualrsquos energybalance so anthropometric measures are used toassess nutritional status (Garn 1962)

Body weight reflects the individualrsquos size and isstrongly influenced by height For this reason whennutritional status is assessed body weight is alwaysexpressed as weight-for-height Currently the twomost widely used ways of expressing weight-for-height are body mass index (BMI) and percentage ofstandard weight (PSW) PSW is derived from ade-quacy of weight-for-height tables developed by a lifeinsurance company (Metropolitan Life InsuranceCompany 1959)

These two indices are calculated as follows

PSW

=

observed weight

yen

100desirable weight-for-height

BMI

=

weight (kg)height

2

(m)

Desirable weight-for-height values were establishedstatistically using life expectancy as the outcome(Society of Actuaries 1959ab) Based on thiscriterion the limits of lsquonormalityrsquo are 90ndash110 PSWNon-pregnant women whose PSW is below 90 are


79



1

pp 77ndash90

considered to be underweight those over 110 areconsidered to be overweight Obesity is defined as aweight-for-height equivalent to 120 or more ofstandard weight The 1959 Metropolitan Life Insur-ance Companyrsquos weight-for-height standards (Metro-politan Life Insurance Company 1959) are widelyused in the United States (Institute of Medicine1990) Latin America including Chile and manyother countries (Mardones and Rosso 1997) How-ever more recently BMI is becoming widely used

Body mass index ranges of normality for non-pregnant women have been proposed using limitsderived from the PSW tables (Institute of Medicine1990) BMI is highly correlated with PSW and isessentially just a different way of presenting informa-tion about the relationship between weight andheight (Working Group 1991)

Use of anthropometric measures in prenatal care

The recognition of the value of anthropometric indi-cators to predict pregnancy outcomes has generatedgreat interest in this previously neglected fieldAlthough many relevant research questions remainunanswered a consensus has been reached regardingthe usefulness of the anthropometric measures asdescribed below

Initial weight-for-height in gestation

Several studies have shown that pre-pregnancyweight-for-height is significantly related to birthweight and gestational age at delivery (Institute ofMedicine 1990 Rosso 1990 Working Group 1991Siega-Ruiz

et al

1994) Thus weight-for-height beforepregnancy or in early pregnancy is considered usefulfor identifying women at nutritional risk

Weight gain during pregnancy

Gestational weight gain reflects the growth of theconceptus and maternal physiological adjustmentssuch as blood volume expansion fluid retention fataccumulation and to a lesser extent increases in leantissue (uterus mammary gland) (Hytten 1981) A

large body of evidence indicates that gestationalweight gain is a determinant of fetal growth (Instituteof Medicine 1990 Abrams

et al

2000) Lower mater-nal net weight gain is associated with an increasedrisk of intrauterine growth retardation and increasedperinatal mortality whereas higher weight gain isassociated with high birth weight and secondarilyprolonged labour shoulder dystocia caesarean deliv-ery birth trauma and perinatal asphyxia (Institute ofMedicine 1990 Parker and Abrams 1992)

Evidence shows that the effect of maternal weightgain on birth weight is modified by the motherrsquos pre-pregnancy weight-for-height Thus while low weightgain puts underweight women at a very high risk ofdelivering

lt

3000 g birth weight infants a similar lowweight gain will have no demonstrable effect in obesewomen On the other hand a large weight gain willreduce the risk of underweight women of deliveringgrowth retarded infants while in obese mothers it willonly increase the maternal risk of hypertension feto-pelvic disproportion and gestational diabetes (Rosso1990)

An adequate weight gain represents an importantgoal in prenatal care because of its influence on fetalgrowth and maternal health Thus health care provid-ers should have access to easy-to-use instruments forsetting desirable weight gain goals for each individualmother and for monitoring weight gain during thecourse of pregnancy

Assessment of maternal nutritional status during the course of pregnancy

In prenatal clinics or other settings where anthropo-metric instruments are available assessment ofmaternal nutritional status should be based onweight-for-height and gestational weight gainAccurate information of length of gestation gener-ally estimated using the date of the last menstrualperiod is essential when applying these anthropo-metric measures

Monitoring of maternal nutritional status duringpregnancy is based on observed changes in bodyweight at the prenatal visits These weight changes areassessed in relation to an expected or desirableweight gain for the entire period of gestation Over

80




1

pp 77ndash90

time the idea of desirable weight gain has undergonesuccessive changes Until the late 1960s and early1970s US pregnant women were encouraged torestrict their weight gain to 8ndash9 kg (Lull andKimbrough 1953) After the importance of maternalnutrition on fetal outcome was recognized the weightgain recommendation was increased to 11ndash12 kg inthe US (Abrams

et al

2000)A study of weight gain of Scottish primigravidas

has greatly influenced concepts of spontaneousweight gain in a well-fed white population (Thomsonand Billewicz 1957) In this study total weight gainbetween the end of the first trimester and term was amean figure of 114 kg Assuming that weight gainduring the first trimester is on average approximately1 kg (Hytten and Leicht 1971) it was concluded thatthe average woman gains 125 kg during pregnancySubsequently and quite erroneously this value wasuniversally adopted as the desirable pregnancyweight gain and was recommended to all womenindependent of their height and pre-pregnancyweight-for-height (Rosso 1990) This was the world-wide recommendation of international organizationsfor many years (World Health Organization 19731985)

The need to define lsquoaveragersquo weight gain consid-ered so important until recently is now of little prac-tical value (Rosso 1990) When the independentinfluences of pre-pregnancy weight and weight gainon birth weight were established it became apparentthat underweight normal weight and overweightwomen have different gestational weight gainrequirements (Institute of Medicine 1990 Rosso1990) Thus it is now well accepted that the previousrecommendation of gaining 11ndash12 kg is valid only forwomen of average height and normal weight-for-height For other women a specific individualizedweight gain target must be established at her firstprenatal visit Based on this weight gain goal thehealth care providers should counsel the mother withrespect to diet and the best use of available foods

Weight gain charts

Several charts and tables establishing weight gaingoals and monitoring weight changes are available

(Institute of Medicine 1990 Rosso 1990) The earliestmodels did not take into consideration maternal pre-pregnancy weight and following criteria accepted atthat time recommended a similar weight gain for allwomen (Oregon WIC Staff 1981 Butman 1982) Themost recent charts incorporate maternal pre-pregnant weight and establish different weight gaintargets for underweight normal and overweightmothers Some of these charts do not take into con-sideration maternal height and therefore recommendsimilar weight gain goals to women of very differentheights (Oregon WIC Staff 1981 Dimperio 1988)Consequently short and tall women are recom-mended to gain proportionately more or less weightrespectively than average height women

One of the charts developed by us (Rosso 1985)solved previous inconsistencies in the application ofweight recommendations to women of differentheights by expressing all weight gain recommenda-tions as PSW Nevertheless the sample size of thatstudy was too small to allow individualized weightgain recommendations in some of the subcategoriesof maternal nutritional status at the beginning ofpregnancy A new study with a larger sample sizeallowed the design of a subsequent chart (Mardonesand Rosso 1997)

A review of the various available charts and tablesby an expert subcommittee of the USA Institute ofMedicine (IOM) concluded that additional researchwas needed to validate some of the concepts andrecommendations of the various charts

including theclassification of women as underweight of normalweight and overweight (Institute of Medicine 1990)

The subcommittee designed weight gain guidelinesby pre-pregnancy BMI These are known as thelsquoIOMrsquos recommended weight-gain rangesrsquo (Instituteof Medicine 1990) This proposal included the follow-ing aspects (1) the use of different charts for under-weight normal weight and overweight women(BMI

lt

198 198ndash260 261ndash290 and

gt

290 respec-tively) and (2) the expression of the total weight gainrecommendation in absolute values with upper andlower limits for each of the charts with the exceptionof the last one (125ndash180 kg 115ndash160 kg 70ndash115 kg and

ge

70 kg respectively) (Institute ofMedicine 1992)


81



1

pp 77ndash90

The cut-off points are similar to those widely usedfor non-pregnant women 90 120 and 135 of the1959 Metropolitan Life Insurance Companyrsquos weight-for-height standards (Institute of Medicine 1990)However unlike the RM chart explained belowthose cut-offs were not validated against pregnancyoutcomes Further the recommendations of the sub-committee for the IOM chart are questionablebecause of the worldwide variability of individualwomenrsquos heights (Krasovec and Anderson 1991) Byexpressing weight gain in absolute values the recom-mendation does not consider proportionality of rec-ommended weight gain for short and tall women Theinclusion in the chart of upper and lower limits ofnormality does not solve the problem On the con-trary it introduces another source of error in judgingadequacy of weight gain in a given mother For exam-ple for underweight women it sets a weight gain tar-get ranging from 125 to 18 kg For a veryunderweight tall woman a 125 kg weight gain may betoo low However for a slightly underweight shortwoman a total weight gain of 18 kg is probably unnec-essarily high In this respect although the IOM rec-ommendations could be useful to assess adequacy ofweight gain in a group of underweight women ofdifferent heights they are inadequate to monitorweight gain in an individual mother The same criti-cism obtains for the weight gain recommendation fornormal and overweight women

The IOMrsquos guidelines have been introduced in theUSA (Institute of Medicine 1992 Abrams

et al

2000)and Canada (Health Canada 1999) Some studieshave examined their possible impact on maternalweight gain during pregnancy and on some perinataloutcomes Evaluations should ideally have an exper-imental design which compares randomly selectedgroups Experimental studies have many practicaldifficulties so most evaluations have been donecomparing cohorts of pregnant women withoutrandomization Cohort studies including those witha large sample sizes have shown favourable results inwomen following IOM weight gain chart guidelines(Parker and Abrams 1992 Siega-Ruiz

et al

1994) Arecent review of observational studies that examinedfetal and maternal outcomes according to IOMrsquosweight gain recommendations in women with a nor-

mal pre-pregnancy weight concluded that the IOMrsquosrecommended ranges are associated with the bestoutcome for both mothers and infants (Abrams

et al

2000) A more recent experimental evaluation con-cluded that the use of the IOMrsquos weight rangesaccompanied by an educational intervention resultsin favourable maternal weight changes during preg-nancy (Polley

et al

2002)The educational intervention in this USA study

was done at the hospital obstetric clinic following thedetermination of BMI

gt

198 by a clinical professional(Polley

et al

2002) The intervention consisted of oraland written information concerning (1) appropriateweight gain (2) exercise and (3) healthy eating Indi-vidual counselling sessions included (1) review ofweight gain chart (2) assessment of current eatingand exercise (ie a 24-h recall or examination of self-monitoring records) with periodic computerizednutrition analysis (3) review of progress towardsbehavioural goals (4) problem-solving (5) instruc-tions in the use of behavioural techniques such asstimulus control or self-monitoring and (6) goal-setting for eating and exercise behaviours

A weight gain standard designed in Chile

The RM chart has been used in Chile since 1987 tomonitor weight gain during pregnancy Besides Chileother Latin American countries ie ArgentinaBrazil Ecuador Panama and Uruguay have alsobeen using this weight gain chart in their prenatalcare programs (Mardones and Rosso 1997) whilstColombia Costa Rica and Peru have been using it inexperimental programs The mean height of Chileanwomen is similar to the mean height of women inmost Latin American countries (Krasovec andAnderson 1991)

The RM chart has gestational age on the horizontalaxis and maternal body weight expressed as PSW onthe vertical axis (Fig 1) Areas of different coloursare used to classify adequacy of weight-for-height forthose underweight of normal weight and overweightand obese mothers (Mardones and Rosso 1997) Theestimation of PSW is derived from an easy to usenomogram (Fig 2) (Rosso 1985) PSW determined in

82




1

pp 77ndash90

this way is much more precise than BMI from avail-able monograms as the PSW scale is much larger

We also designed this chart using BMI (Fig 3) afterdemonstrating that PSW has a correlation coefficientof nearly 1 with BMI in the original database(Mardones

et al

1999) in agreement with previousresearch (Working Group 1991)

The weightheight limits which classify the individ-uals as normal underweight overweight and obesewere determined using actual data from 1745 healthyadult women delivering their singleton babies at 39ndash41 weeks of gestation (Mardones and Rosso 1997)Women in this study were enrolled in the prenatalclinics of the south-east health zone of Santiago ChileInclusion criteria were 20 years old and older para0ndash5 non-smokers non-consumers of alcoholic bever-ages and free of obstetric and medical complicationsknown to affect fetal growth Only babies deliveredat 39ndash41 weeks of gestation were included in the firstanalysis (Mardones and Rosso 1997) because if birthweight is between 3 and 4 kg they are thought to be

optimally grown (Institute of Medicine 1990) Thispopulation was ethnically mixed ie Amerindian andHispanic ancestry and socio-economically mixed ie86 from the low income group covered by the publichealth sector (70 of the total Chilean population)and 14 from a middle income population (Mar-dones and Rosso 1997) Weightheight limits at weeks10 and 40 of gestation for both PSW and BMI areshown in Table 1

The critical body mass has been defined whendesigning the RM chart as the weight-for-height areaduring gestation at which the resulting mean birthweight is similar to the mean birth weight of a healthypopulation of pregnant women (Mardones and Rosso1997) This area is equivalent in the RM chart to thediagnosis of weight in the normal range shown as the

Fig 1

The Rosso and Mardones chart for guiding weight gain duringpregnancy (modified from Mardones and Rosso 1997) Weight forheight is expressed as percentage of standard weight (PSW)

Fig 2

Nomogram to determine adequacy of weight for height andto calculate desirable total weight gain during pregnancy (Rosso 1985)Reproduced with permission by the

American Journal of Clinical Nutrition

copy Am J Clin Nutr American Society of Clinical Nutrition

174

172

170

168

166

164

162

160

158

156

154

152

150

148

146

144

142

140

100

95

90

85

80

75

70

65

6060

55

50

45

40

35

3070

75

80

85

90

95

100

105

110

115

120

125

130

135

Height(cm)

Weight(kg)

Percentage ofStandard Weight()


83



1

pp 77ndash90

green area in Figs 1 and 3 Women in the normalrange at the beginning and at the end of pregnancy

delivered newborns with birth weight 3455

plusmn

383 g(Mean

plusmn

SD) and 3450

plusmn

363 g (Mean

plusmn

SD) respec-tively values which were very similar to the figure forthe entire population 3428

plusmn

398 g (Mean

plusmn

SD)(Mardones and Rosso 1997) Malnutrition diagnoses(Table 1) increase the risk of delivering infants ofbirth weight

lt

3000 g or

ge

4000 g (Tables 2 and 3)These data validate previous recommendations

that maternal weight-for-height at term should be atleast equivalent to PSW 120 (BMI 266) (Rosso 1985)Pregnant underweight women who were able toreach this goal had infants significantly heavier thanwomen whose body mass increment remained belowthis value A similar conclusion reached in black andHispanic women living in the US suggests that theproposed limit is valid across some ethnic and culturalboundaries (Hickey

et al

1990) However this infor-mation does not invalidate the need to determinewhether the chartrsquos weight recommendations are

Fig 3

The Rosso and Mardones chart for guiding weight gain duringpregnancy (modified from Mardones

et al

1999) Weight for height isexpressed as body mass index (BMI)

Table 1

BMI and PSW cut-offs points of the RM chart for thenutritional classification of women at the beginning and at the end ofpregnancy (Mardones and Rosso 1997 Mardones

et al

1999)

BMI PSW

Week 10Underweight

lt

2115

lt

95Normal 2115ndash2449 95ndash109Overweight 245ndash2673 110ndash119Obese

gt

2673

gt

120Week 40

Underweight

lt

2655

lt


gt

3003

gt

1348

BMI body mass index PSW percentage of standard weight RMRosso and Mardones

Table 2

Odd ratios (OR) and confidence intervals (CI 95) for birthweights

lt

3000 g in low weight women diagnosed by the Rosso andMardones (RM) chart at the beginning and at the end of pregnancy(Mardones

et al

1999) (

n

=

1745 women)

OR CI 95

Week 10Underweight 1650 1414ndash1925Normal 1


Table 3


ge

4000 g in overweight and obese women diagnosed by theRosso and Mardones (RM) chart at the beginning and at the end ofpregnancy (Mardones

et al

1999) (

n

=

1745 women)

OR CI 95

Week 10Normal 1Overweight 1395 1249ndash1557Obese 2311 1751ndash3050


84




1

pp 77ndash90

more universally applicable as suggested by otherauthors (Gueri

et al

1982)For the Chilean population included in this study

the critical initial weight-for-height was established asPSW 95 (BMI 2115) a value somewhat higher thanthe traditional limit of PSW 90 to define being under-weight in a non-pregnant woman

Actual weight increments in underweight womenwho reached the green area at the end of pregnancywere used to design lsquochannelsrsquo to guide ideal weightgain see in Figs 1 and 3 lines that begin at week 10of gestation in the subcategories of PSW Weight gainchannels for overweight and obese women are tenta-tive as in the original population most such womendid not reach the green area at the end of pregnancyTherefore and assuming that pregnancy is not a timefor dieting nor to aggravate a pre-existing obesity thecorresponding lsquodesirablersquo weight increment channelswere designed based on the physiological weightchanges that take place during a normal pregnancy(Niswander 1981)

The RM chart is only valid in fully grown womenwith singleton pregnancies Its use in adolescent preg-nancies remains to be determined The height andweight ranges included in the nomogram (140ndash170 cm and 30ndash100 kg) preclude its use in women whoexceed these values In order to include this popula-tion the nomogram should be modified and validated

Attendance at clinics for antenatal visits wherethey can be weighed may not be possible in every partof the world Pharmacies or markets where appropri-ate equipment for weightheight calculations may beavailable could be alternatives

The RM chart starts at week 10 of gestation Weightgain is modest in the first weeks of pregnancy andwomen frequently present for their initial pregnancycheck-up at around 10 weeks of gestation when useof the chart is appropriate In addition women whopresent to health care services later than others caneasily be allocated into specific weightheight catego-ries in the RM chart and still be guided along theirweight increment

The mean maternal weight gain 126

plusmn

61 kg(mean

plusmn

SD) observed in the entire sample of lowincome Chilean women used to derive the RM chartis higher than figures reported for other developing

countries (Schieve

et al

1998) This may be partiallydue to the inclusion and exclusion criteria that elim-inated gravid women with medical and obstetric com-plications Also nutritional status and other maternalfactors such as heavy manual work may have beenbetter in the Chilean women than in those of lowincome populations from other countries reported inthe literature Mean maternal weight gain of womenin the green area of the RM chart correspondingto normal nutritional status was 127

plusmn

52 kg(mean

plusmn

SD) a similar figure than the total studygroup

Mean birth weight at term (3428

plusmn

398 g) was alsohigher in this study than that reported in most devel-oping countries (Puffer and Serrano 1987) This dif-ference can be attributed to exclusion criteria leadingto a greater maternal weight gain and the absence ofmaternal complications Mean birth weight in healthypopulations would be affected mainly by the propor-tions of underweight and obese women or the meanPSW at the end of pregnancy (Rosso 1991) so use ofthe chart elsewhere is appropriate from this point ofview

Recent information from Chile

The Chilean National Health Services adopted theRM chart in 1987 and information on maternal nutri-tional status as classified by the chart is now avail-able for the entire country Annual proportions ofpregnant women mostly middle and low incomewomen in the different weight-for-height categoriesare reported from women at different gestationalages taken in the month of December during routinecheck-ups National data are available for the 1987ndash2001 period for live births including information onbirth weight live births with missing data on birthweight were only 152 of the total in 1987 and010 in 2001 Unfortunately the combined registra-tion of birth weight and maternal nutritional statusfor each individual live birth is lacking

The 30 of women attending private healthservices and the military health services belong to awealthier population than the 70 of women underthe national public health service (National HealthFund 2003) Generally national health information is


85



1

pp 77ndash90

not registered according to the specific health systemof each patient Nevertheless most national healthindices are considered representative of the 70 andvice versa as the remaining 30 would alter the over-all data very little (Rajs 2004) In spite of this consid-eration the prevalence report for the month ofDecember each year is a mixture of women enteringcheck-ups for the first time and women being moni-tored during pregnancy with two or more check-upsThis fact does not allow for conclusions regardingthe possible RM chart effect the former would be theexpression of the pre-pregnancy influences and thelatter would be mostly affected by the pregnancyperiod including the RM chart possible effect Fur-thermore the occurrence of many other changesassociated with a decade of substantial economicgrowth in the country and improved family incomeprevents the possibility of drawing any conclusionwith respect to the efficacy of the use of the RM chartFor example the population living below the povertyline declined from over 40 at the end of the 1980sto 206 in 2000 (Ministry of Planning 2000) For allthese reasons Chile is now considered to be in thephase of nutritional transition (Albala

et al

2002)Although the previous comments preclude conclu-

sions to be drawn on the possible association betweennational anthropometric changes and the use of theRM chart the evolution of maternal nutritional statusand specific birth weight categories between 1987 and2001 are important demographic changes as dis-cussed below Observational and experimental stud-ies on the possible impact of using the RM chart arealso discussed

Maternal underweight diagnosis and birth weight ltltltlt3000 g

During the observation period the proportions ofinfants of birth weight lt3000 g and underweight preg-nant women have decreased at similar rates In 1987the incidence of birth weight lt3000 g was 264 andthe prevalence of underweight pregnant women was257 By contrast in 2001 the incidence of birthweights lt3000 g was 202 and the proportion ofunderweight pregnant women was 133 (NationalInstitute of Statistics Chile 1987ndash2001 Ministry of

Health Nutrition Unit 2002) Thus a 235 reduc-tion of birth weight lt3000 g and a 48 reduction ofunderweight pregnant women have been observed

Most infants diagnosed as intrauterine growthretarded fall within birth weight range lt3000 g(Puffer and Serrano 1987) which in Chile results inan infant mortality rate of approximately 20 per thou-sand live births double the national figure (NationalInstitute of Statistics Chile 1987ndash2001) Between1987 and 2001 the percentage for birth weight lt2500 gdecreased from 65 to 53 Thus the drop in thepercentage of lt3000 g birth weight babies observedin the same period mostly reflects a decrease in the2500ndash2999 g babies category Some authors considerthat the change in this category is linked to maternalsocial and nutritional factors (Puffer and Serrano1987)

Being underweight during pregnancy as defined bythe RM chart triggers a special education package toimprove home diet Although financial restrictionmay limit the improvement of the caloric and proteinintake of the home the educational intervention hasbeen shown to be effective in an observational study(Duraacuten et al 1999) This national educational inter-vention is initiated by diagnosis of being underweightoverweight or obese during the regularly scheduledclinic visits usually overseen by midwives Thewomen are then sent to a nutritionist in the samehealth clinic who performs a 24-h dietary recall anda food-frequency questionnaire She then advisesappropriate weight gain during pregnancy ie follow-ing the RM chart lsquochannelsrsquo of weight gain to beachieved by healthy eating and sometimes exercise

This improvement in dietary intake is supported bythe greater contribution of food through the NationalFood Supplementation Program (NFSP) The NFSPdelivers 2 kg of powdered milk and 2 kg of ricemonthly to underweight pregnant women otherwomen receive just 1 kg of powdered milk

Observational studies conclude that this interven-tion in underweight mothers has a positive associa-tion with maternal food intake weight gain and theincidence of birth weights lt3000 g (Robinovitch et al1995 Duraacuten et al 1999 Mardones 2003) Neverthe-less other factors could have influenced the favour-able results in those observational studies Therefore

86 F Mardones and P Rosso

copy Blackwell Publishing Ltd 2005 Maternal and Child Nutrition 1 pp 77ndash90

a causal association with the observed reduction ofbirth weight lt3000 g needs the additional proof ofexperimental or quasi-experimental studies

Data from an experimental study conducted inChile support the possibility of a positive effect ofmultimicronutrient fortification of powdered milk onmildly undernourished women such as those in thePSW category 90ndash94 (Mardones-Santander et al1988) Underweight pregnant women as defined bythe RM chart entered the study at 144 plusmn 3(mean plusmn SD) weeks of gestation with PSW 90 plusmn 6(mean plusmn SD) The standard 26 fat milk powderused in the national program was delivered to thecontrol group The experimental group received asupplement consisting of milk powder fortified withmicronutrients At the end of pregnancy the meanPSW in the control group was 111 whereas in theexperimental group it was 1127 The incidence of abirth weight lt3000 g was 399 in the control groupand 325 in the experimental group (P lt 005) Onaverage neither group reached the lsquocritical bodymassrsquo and they gained 123 kg plusmn 46 kg and113 kg plusmn 52 kg (P lt 005) in the experimental andcontrol groups respectively Nevertheless the wideSD for weight gain suggests that some of them espe-cially in the experimental group may have reachedthe critical body mass supporting the improved fetalgrowth

The multimicronutrient fortified milk used in theSantiago study had 43 mg of iron sulfate per 100 gof powder (Mardones-Santander et al 1988) thisamount of iron made this product susceptible to fatoxidation inhibiting the introduction of similarly for-tified powdered milks in Chile New products that useaminochelated iron are recently available permittingsimilar iron fortification without technological prob-lems (Mardones et al 2004) The majority of LatinAmerican countries using the graph are providingnon-fortified powdered milk to pregnant women

Ethically it is not possible to perform an experi-ment with a control group not receiving the foodsupplement however a de facto analogous groupcomprised spontaneous non-consumers of milk dur-ing pregnancy (Mardones-Santander et al 1988) Thisquasi-experimental comparison showed a positiveassociation between food supplements consumption

and birth weight The proportions of birth weightlt3000 g were 399 and 61 respectively amongconsumers and non-consumers of the regular foodsupplement Women suffering from lactose intoler-ance have a variable prevalence among different pop-ulations Possibly the majority of the 10 of womenwho did not consume milk in the Santiago study suf-fered from lactose intolerance This aspect is notimportant for the possible efficacy of this kind ofintervention because most dairy companies nowa-days produce lactose free powdered milk

Positive cost-effect benefit of the experimental andthe quasi-experimental results have been calculated(Mardones and Zamora 1990 Mardones-Santanderet al 1991)

Micronutrient supplementation during pregnancylsquohas been paid little attention until the late 1990sexcept for the constant concern about the high prev-alence of maternal iron deficiencyrsquo (United NationsAdministrative Committee on Coordination Sub-Committee on Nutrition 2000a) A recent review hasconcluded that the Santiago study was one of onlyfour trials on dietary supplementation to have suc-cessfully reduced or prevented low birth weight(United Nations Administrative Committee on Coor-dination Sub-Committee on Nutrition 2000b) Wehave compared nutritional interventions preventingintrauterine growth retardation as published by DeOnis and colleagues (De Onis et al 1998) with theoutcomes of the Santiago study concluding that ourresults were the best in preventing intrauterinegrowth retardation (Mardones-Santander et al 1999Mardones-Santander et al 2000)

Nutritional supplementation with micronutrientsfor mildly underweight women seems justified Infrankly or greatly underweight women it might beexpected that a high caloric supplement would havea greater effect as concluded from the results of theGambia study (United Nations Administrative Com-mittee on Coordination Sub-Committee on Nutri-tion 2000b) With regard to the possible mechanismsof the effect on intrauterine growth restriction wehave proposed that the micronutrient content of thefortified milk powder may lead to higher fluid reten-tion and greater plasma volume expansion Thishigher plasma volume expansion may favourably

Weight gain chart for pregnant women 87


influence fetal growth (Rosso and Salas 1994) a viewshared by others for the Santiago study (Institute ofMedicine 1990 Susser 1991) In fact women in theexperimental group in our study gained on average1 kg more during pregnancy than women in the con-trol group Nevertheless this weight difference disap-peared 24ndash48 h after delivery probably explained byhigher fluid retention We have also demonstratedthat maternal body water and therefore fat-free-mass near term is the most important variableinfluencing birth weight (Mardones-Santander et al1998)

A substantial proportion of women in both devel-oped and underdeveloped countries have diets withlower than recommended amounts of certain micro-nutrients which have been associated with pregnancyoutcome The absence of these micronutrients eitherbecause of poor diet or impaired absorption mayinfluence these mechanisms

Maternal overweight and obese diagnoses and birth weight gegegege4000 g

Chile had a national incidence of 605 for birthweight ge4000 g in 1987 and 107 in 2001 (NationalInstitute of Statistics et al 1987ndash2001) Over the sameperiod estimated annual overweight and obese preg-nant women numbers in the public health systemhave increased from 188 and 129 respectivelyin 1987 to 218 and 326 in 2001 (Ministry ofHealth Nutrition Unit 2002) Therefore the com-bined prevalence for overweight and obese pregnantwomen has increased from 317 to 544

The increases over time in birth weight ge4000 g inbeing overweight and in obese women proportionsare relatively similar Nevertheless the proportion ofbirth weights ge4000 g is small in comparison with theabove mentioned proportion of malnutrition thisobservation about macrosomic births has beendescribed elsewhere (Lu et al 2001)

Being overweight or obese also triggers an educa-tional intervention with a smaller contribution offood through the NFSP which delivers just 1 kg ofpowdered milk per month to these women The policyof delivering less milk to overweight or obese womencould simply worsen dietary quality rather than

decreasing weight gain Nevertheless the educationalintervention has been shown to be successful inreducing caloric consumption (Duraacuten et al 1999)

The annual prevalence of overweight or obesepregnant women has continued to grow The increasein obesity has been described around the world andhas been shown to be a modern epidemic (Albalaet al 2002) For example in Birmingham USA datafrom 53 080 pregnant women has shown that the pro-portion with a BMI gt 29 at the first prenatal visitincreased from 163 in 1980 to 364 in 1999 (Luet al 2001) As the BMI cut-off for obesity is close to27 at the beginning of pregnancy on the RM chart itseems that obesity figures diagnosed with a morestringent criterion in the USA are much higher thanin Chile Evidently the proportion of obese womenhas more than doubled as has similarly been observedin Chile The high figures observed both in Chile andin Birmingham USA are probably influenced by theobesity rise of the general population in the pre-pregnant period On the other hand large-for-datesinfants increased in Birmingham from 115 to139 a lower proportion than the change in mater-nal nutritional status this observation is similar towhat happened in Chile relating to birth weightge4000 g

The limited influence of obesity on macrosomicbirths may be due to different factors Overweightand obese pregnant women attending the publichealth system in Chile frequently have low amountsof micronutrients in their diet (Duraacuten et al 1999) andanaemia is also observed in this group (Mardoneset al 2003b) These factors could lead to reduced fetalgrowth as proposed by Allen and Gillespie (UnitedNations Administrative Committee on CoordinationSub-Committee on Nutrition 2000b) and also byBarker using data from Finland (Forsen et al 1997Barker 1998) Indeed they contribute to the incidenceof term birth weight lt3000 g in Chile (Robinovitchet al 1995 Mardones and Rosso 1997) Alternativelyit has been observed that overweight and obesewomen have more preterm deliveries mostly fromcaesarean sections than women with normal weightheight (Robinovitch et al 1995 Lu et al 2001 Youngand Woodmansee 2002) These preterm deliverieshave reduced weight at birth (Silva et al 2001) These



possibilities could partially explain the less thanexpected rise in birth weights ge4000 g particularly asChile had the highest caesarean section rate (40 in1997) of 12 Latin America countries studied (Belizanet al 1999)

Overweight and obese mothers at the end of preg-nancy as defined by the RM chart may increase thecardiovascular mortality risk in their male offspringwhen adults as observed in Finland (Forsen et al1997)

Conclusions

There is convincing evidence that the effect of mater-nal weight gain on birth weight is influenced by themotherrsquos pre-pregnancy weight-for-height Thusefforts to prevent malnutrition in pregnant womenshould begin well before conception Because of itsinfluence on fetal growth and maternal health anadequate weight gain represents an important goal ofprenatal care

Over time the definition of desirable weight gainhas undergone successive changes When the inde-pendent influences of pre-pregnancy weight andweight gain on birth weight were established itbecame apparent that underweight normal weightand overweight women require different weightgains Thus it is now well accepted that the previousrecommendation of gaining 11ndash12 kg is valid only forwomen of average height and normal weight-for-height For other women a specific individualizedweight gain target must be established at her firstprenatal visit

It is concluded that a chart for pregnancy weightgain based on weight-for-height using PSW or BMIis better in practice than simple recommendations fortarget amount to gain as it accounts for the differ-ences in womenrsquos size The RM chart fits this needbecause its weight gain recommendations are propor-tional to maternal height

The RM chart has been used in Chile since 1987and since the 1990s in other Latin American coun-tries There has been an undoubted improvement inboth maternal anthropometry and birth weight valuesin Chile between 1987 and 2001 However the pres-ence of many other influencing factors preclude

reaching specific conclusions on the possible effect ofthe RM chart However other Chilean observationaland experimental studies do lend evidence as to thefavourable effects of its use

The RM chart can be used around the worldbecause it covers most of the maternal height rangeNevertheless we suggest validation studies be under-taken in countries where women have differentmaternal heights or body frames from Chileanwomen in whom the chartrsquos weight recommenda-tions have been demonstrated as applicable

References

Abrams B Altman SL amp Pickett KE (2000) Pregnancy weight gain still controversial American Journal of Clin-ical Nutrition 71(Suppl) 1233Sndash1241S

Albala C Vio F Kain J amp Uauy R (2002) Nutrition tran-sition in Chile determinants and consequences Public Health Nutrition 5 123ndash128

Barker DJP (1998) Mother Babies and Health in Later Life 2nd edn Churchill Livingstone Edinburgh

Belizan JM Althabe F amp Barros FC (1999) Rates and implications of caesarean sections in Latin America eco-logical study British Medical Journal 319 1397ndash1400

Butman M (1982) Prenatal Nutrition A Clinical Manual WIC Program Massachusetts Department of Public Health Boston

De Onis M Villar J amp Guumllmezoglu M (1998) Nutritional interventions to prevent intrauterine growth retardation evidence from randomized controlled trials European Journal of Clinical Nutrition 52 S1 S83ndashS93

Dimperio D (1988) Prenatal Nutrition Clinical Guidelines for Nurses March of Dimes Birth Defects Foundation White Plains NY

Duraacuten E Soto D Asenjo G Pradenas F amp Quiroz V (1999) Diet evaluation during pregnancy and its relation to nutritional status (Evaluacioacuten de la dieta de embaraza-das de aacuterea urbana y su relacioacuten con el estado nutricio-nal) Revista Chilena de Nutricion 26 62ndash69

Forsen T Ericksonn JG Tuomilehto J Teramo K Osmonde C amp Barker DJP (1997) Motherrsquos weight in pregnancy and coronary heart disease in a cohort of Finnish men follow up study British Medical Journal 315 837ndash884

Garn SM (1962) Anthropometry in clinical evaluation of nutritional status American Journal of Clinical Nutrition 11 418ndash432

Gueri M Jutsum P amp Sorhaindo B (1982) Anthropometric assessment of nutritional status in pregnant women a reference table of weight-for height by week of preg-



nancy American Journal of Clinical Nutrition 35 609ndash616

Health Canada (1999) Nutrition for a Healthy Pregnancy National Guidelines for the Childbearing Years Minister of Public Works and Government Services Canada Ottawa

Hickey CA Uauy R Rodriguez LM amp Jennings LW (1990) Maternal weight gain in low-income Black and Hispanic women evaluation by use of weight-for-height near term American Journal of Clinical Nutrition 52 938ndash943

Hytten FE (1981) Weight gain in pregnancy In Clinical Physiology in Obstetrics (eds FE Hytten amp G Chamberlain) pp 193ndash233 Blackwell Oxford

Hytten FE amp Leicht I (1971) The Physiology of Human Pregnancy Blackwell Oxford

Institute of Medicine National Academy of Sciences (1990) Nutrition During Pregnancy National Academy Press Washington DC

Institute of Medicine National Academy of Sciences (1992) Nutrition During Pregnancy and Lactation An Implemen-tation Guide National Academy Press Washington DC

Krasovec K amp Anderson MA (1991) Appendix B mean height weight and body mass index of nonpregnant women 18 years of age or more in developing countries and the US In Maternal Nutrition and Pregnancy Out-comes Scientific Publication Ninfin 529 (eds K Krasovec amp MA Anderson) pp 208ndash211 Pan American Health Organization Washington DC

Lu GC Rouse DJ Dubard M Cliver S Kimberlin D amp Hauth JC (2001) The effect of the increasing prevalence of maternal obesity on perinatal morbidity American Journal of Obstetrics and Gynecology 185 845ndash849

Lull CV amp Kimbrough RA (1953) Clinical Obstetrics Lippincott Philadelphia

Mardones F (2003a) Evolution of maternal anthropometry and birth weight in Chile 1987ndash2000 (Evolucioacuten de la antropometriacutea materna y del peso de nacimiento en Chile 1987ndash2000) Revista Chilena de Nutricion 30 122ndash131

Mardones F Rioseco A Ocqueteau M Urrutia MT Javet L Rojas I et al (2003b) Anaemia in pregnant women of Puente Alto Chile (Anemia en las embarazadas de Puente Alto Chile) Revista Meacutedica de Chile 131 520ndash525

Mardones F amp Rosso P (1997) Design of a weight gain chart for pregnant women (Disentildeo de una curva patroacuten de incrementos ponderales para la embarazada) Revista Meacutedica de Chile 125 1437ndash1448

Mardones F Rosso P Marshall G Villarroel L amp Bastiacuteas G (1999) Comparison of two weight-for-height indices in pregnant women (Comparacioacuten de dos indicadores de la relacioacuten peso-talla en la embarazada) Acta Pediaacutetrica Espantildeola 57 501ndash506

Mardones F Urrutia MT Villarroel L Rioseco A Bastias G Castillo O et al (2004) Fetal growth in

underweight Chilean pregnant women using a new milk-based (Suppl) (Mamaacuten) X International Congress of Auxology Florence Italy Book of Abstracts P-57 p 146

Mardones F amp Zamora R (1990) Socio-economic evalua-tion of powdered milk delivery to pregnant women in Chile (Evaluacioacuten socio-econoacutemica de la entrega de leche lsquoPuritarsquo a la embarazada en Chile) Revista Meacutedica de Chile 118 1043ndash1051

Mardones-Santander F Marshall G Rosso P amp Uiterwaal D (2000) A reply to MS Kramer Isocaloric protein sup-plementation during pregnancy (letter) European Journal of Clinical Nutrition 54 803

Mardones-Santander F Rosso P Stekel A Ahumada E Llaguno S Pizarro F et al (1988) Effect of a milk-based food supplement on maternal nutritional status and fetal growth in underweight Chilean women American Journal of Clinical Nutrition 47 413ndash419

Mardones-Santander F Rosso P Uiterwaal D amp Marshall G (1999) Nutritional interventions to prevent intrauter-ine growth retardation evidence from randomized con-trolled trials (letter) European Journal of Clinical Nutrition 53 970ndash971

Mardones-Santander F Rosso P amp Zamora R (1991) Cost-effectiveness of a nutrition intervention for pregnant women Nutrition Research 11 295ndash307

Mardones-Santander F Salazar G Rosso P amp Villarroel L (1998) Maternal body composition near term and birth weight Obstetrics and Gynecology 91 873ndash877

Metropolitan Life Insurance Company (1959) New weight standards for men and women Statistics Bulletin Metro-politan Life Insurance Company 40 1ndash4

Ministry of Health Nutrition Unit (2002) Nutritional Situa-tion of the Maternal and Child Population Covered by the Public System Ministry of Health Nutrition Unit Mimeo Santiago

Ministry of Planning Chile (2000) Social Department National Survey of Social Conditions (CASEN) httpwwwmideplancl

National Health Fund Chile (2003) Estimations of Covered Population by the Public Health System National Health Fund Ministry of Health Department of Studies Mimeo Santiago

National Institute of Statistics Chile (1987ndash2001) Vital Statistics Web site httpwwwinecl

Niswander KR (1981) Obstetrics 2nd edn Little Brown and Company Boston

Oregon WIC Staff (1981) WIC Program Manual Oregon Health Division Department of Human Resources Portland Oregon

Parker JD amp Abrams B (1992) Prenatal weight gain advice an examination of the recent prenatal weight gain recommendations of the Institute of Medicine Obstetrics and Gynecology 79 664ndash669



Polley BA Wing RR amp Sims CJ (2002) Randomized controlled trial to prevent excessive weight gain in preg-nant women International Journal of Obesity and Related Metabolic Disorders 26 1494ndash1502

Puffer RR amp Serrano CV (1987) Patterns of Birth Weight PAHO Scientific Publication No 504 Pan American Health Organization Washington DC

Rajs D (2004) Head Statistics Unit Ministry of Health Chile Personal communication

Robinovitch J Rubio E Saacuteez J amp Ramiacuterez M (1995) Body weight influence on pregnancy and perinatal outcomes (Influencia del peso corporal en el embarazo y resultado perinatal) Revista Chilena de Obstetricia y Ginecologia 60 151ndash167

Rosso P (1985) A new chart to monitor weight gain during pregnancy American Journal of Clinical Nutrition 41 644ndash652

Rosso P (1990) Nutrition and Metabolism in Pregnancy Oxford University Press New York

Rosso P (1991) Weight-for-heightbody mass index in preg-nant women In Maternal Nutrition and Pregnancy Out-comes Scientific Publication Ninfin 529 (eds K Krasovec amp MA Anderson) pp 173ndash185 Pan American Health Organization Washington DC

Rosso P amp Salas S (1994) Mechanisms of fetal growth retar-dation in the underweight mother In Nutrient Regulation During Pregnancy Lactation and Infant Growth (eds LH Allen JC King B Loumlnnerdal) pp 1ndash9 Plenum Press New York

Schieve LA Cogswell ME amp Scanlon KS (1998) An empiric evaluation of the Institute of Medicinersquos preg-nancy weight gain guidelines by race Obstetrics and Gynecology 91 878ndash884

Siega-Ruiz AM Adair LS amp Hobel CJ (1994) Institute of Medicine maternal weight gain recommendations and pregnancy outcome in a predominantly Hispanic population Obstetrics and Gynecology 84 565ndash573

Silva AA Lamy-Filho F Alves MT Coimbra LC Bettiol H amp Barbieri MA (2001) Risk factors for low birthweight in north-east Brazil the role of caesarean section Paediatric and Perinatal Epidemiology 15 257ndash264

Society of Actuaries (1959a) Build and Blood Pressure Study Vol I Society of Actuaries Chicago

Society of Actuaries (1959b) Build and Blood Pressure Study Vol II Society of Actuaries Chicago

Susser M (1991) Maternal weight gain infant birth weight and diet causal sequences American Journal of Clinical Nutrition 53 1384ndash1396

Thomson AM (1983) Fetal growth In Obstetrical Epide-miology (eds SL Barron amp AM Thomson) pp 89ndash142 Academic Press Inc (London) Ltd London

Thomson AM amp Billewicz WZ (1957) Clinical significance of weight trends during pregnancy British Medical Journal 1 243ndash247

United Nations Administrative Committee on Coordina-tion Sub-Committee on Nutrition (2000a) Nutrition Pol-icy Paper 19 What Works A Review of the Efficacy and Effectiveness of Nutrition Interventions (eds LH Allen amp SR Gillespie) UNU ACCSCN in collaboration with the Asian developmental Bank Manila Geneva

United Nations Administrative Committee on Coordina-tion Sub-Committee on Nutrition (2000b) Nutrition Pol-icy Paper 18 Low Birthweight Report of a Meeting in Dhaka Bangladesh on 14ndash17 June 1999 (eds J Pojda amp L Kelly) UNU ACCSCN in collaboration with ICDD Geneva

Working Group (1991) Summary and recommendations In Maternal Nutrition and Pregnancy Outcomes PAHO Scientific Publication Ninfin 529 (eds K Krasovec amp MA Anderson) pp 197ndash203 Pan American Health Organization Washington DC

World Health Organization (1973) Energy and Protein Requirement Report of a joint FAOWHO Expert Con-sultation Technical Report Series no 522 World Health Organization Geneva

World Health Organization (1985) Energy and Protein Requirements Report of a Joint FAOWHOUNU Expert Consultation Technical Report Series no 724 World Health Organization Geneva

World Health Organization (2003) Diet nutrition and chronic disease in context In Diet Nutrition and the Pre-vention of Chronic Diseases (WHO Technical Report Series No 916) pp 30ndash53 WHO Geneva

Young TK amp Woodmansee B (2002) Factors that are asso-ciated with cesarean delivery in a large private practice the importance of prepregnancy body mass index and weight gain American Journal of Obstetrics and Gynecol-ogy 187 312ndash318

78




1

pp 77ndash90

addition given their sensitivity to weight and bodyimage issues women are likely to request adviceabout weight increment during pregnancy (Abrams

et al

2000)In Chile during the 1980s we developed an instru-

ment that classifies mothers according to their nutri-tional status allowing monitoring of adequacy ofweight gain during gestation (Mardones and Rosso1997) This instrument [the Rosso and Mardones(RM) chart] which is a development of a previouschart (Rosso 1985) enables the identification at anygestational age of mothers at risk of delivering eithersmall or large for gestational age babies and setsweight gain goals for each individual mother Thesegoals can then be used by health personnel to monitoradequacy of weight gain and to provide either dieteticcounselling or food supplements The chart can beeasily used in prenatal clinics of developing countriesand is currently used in several Latin Americacountries

In the present paper the usefulness of the RMchart in targeting interventions aimed at preventinglow or high birth weights is analysed and the featureswhich make it particularly useful in field conditionsdiscussed Birth weight of less than 3000 g is used todefine small for gestational age infants Weight-for-gestation charts and tables published by Lubchencoand many subsequent workers are frequentlyadopted to define small for gestational age infantsusually those below the 10th centile at a given gesta-tion (Thomson 1983) The majority of infants diag-nosed as small for gestational age or intrauterinegrowth retarded weigh less than 3000 g cases mostaffected by maternal nutritional status and social con-ditions are those in the 2500ndash2999 category (Pufferand Serrano 1987) A birth weight of

ge

4000 g definesmacrosomic or large for gestational age infants Thisconcurs with other weight-for-gestation charts defin-ing large for gestational age infants as those over the90th centile at a given gestation All infants diagnosedas large for gestational age fall within the birth weightof

ge

4000 g in most texts (Thomson 1983)The above mentioned birth weight categories carry

increased mortality and morbidity risks during thefirst year of life (Institute of Medicine 1990) Furtherthere are other long-term outcomes such as suscepti-

bility to chronic disease in later life lsquoThere is consid-erable evidence mostly from developed countriesthat intrauterine growth retardation is associatedwith an increased risk of coronary heart diseasestroke diabetes and raised blood pressure Large sizeat birth is also associated with an increased risk ofdiabetes and cardiovascular diseasersquo (World HealthOrganization 2003)

We discuss and comment on the joint evolution inChile of maternal anthropometry and birth weightvalues between 1987 and 2001 following the adoptionof the RM chart by the Chilean National Health Ser-vices Many other factors may have influenced thisevolution so it is not possible to identify the specificeffects of the RM chart However observational andexperimental studies are presented as favourable evi-dence for its use

Anthropometry

The anthropometric characteristics of individualsreflect their body mass and the proportion of fat andlean tissue Body weight and the proportion of fat orlean tissue are determined by the individualrsquos energybalance so anthropometric measures are used toassess nutritional status (Garn 1962)

Body weight reflects the individualrsquos size and isstrongly influenced by height For this reason whennutritional status is assessed body weight is alwaysexpressed as weight-for-height Currently the twomost widely used ways of expressing weight-for-height are body mass index (BMI) and percentage ofstandard weight (PSW) PSW is derived from ade-quacy of weight-for-height tables developed by a lifeinsurance company (Metropolitan Life InsuranceCompany 1959)

These two indices are calculated as follows

PSW

=

observed weight

yen

100desirable weight-for-height

BMI

=

weight (kg)height

2

(m)

Desirable weight-for-height values were establishedstatistically using life expectancy as the outcome(Society of Actuaries 1959ab) Based on thiscriterion the limits of lsquonormalityrsquo are 90ndash110 PSWNon-pregnant women whose PSW is below 90 are


79



1

pp 77ndash90







et al





et al



lt






80




1

pp 77ndash90


et al




Weight gain charts







lt


gt


ge



81



1

pp 77ndash90



et al


et al



et al


et al



gt


et al





82




1

pp 77ndash90



et al





Fig 1


Fig 2




174

172

170

168

166

164

162

160

158

156

154

152

150

148

146

144

142

140

100

95

90

85

80

75

70

65

6060

55

50

45

40

35

3070

75

80

85

90

95

100

105

110

115

120

125

130

135

Height(cm)

Weight(kg)



83



1

pp 77ndash90



plusmn

383 g(Mean

plusmn

SD) and 3450

plusmn

363 g (Mean

plusmn


plusmn

398 g (Mean

plusmn


lt

3000 g or

ge



et al


Fig 3


et al


Table 1


et al

1999)

BMI PSW

Week 10Underweight

lt

2115

lt


gt

2673

gt

120Week 40

Underweight

lt

2655

lt


gt

3003

gt

1348


Table 2


lt


et al

1999) (

n

=

1745 women)

OR CI 95



Table 3


ge


et al

1999) (

n

=

1745 women)

OR CI 95



84




1

pp 77ndash90


et al








plusmn

61 kg(mean

plusmn


countries (Schieve

et al


plusmn

52 kg(mean

plusmn



plusmn






85



1

pp 77ndash90


et al



































Conclusions







References






































































79



1

pp 77ndash90







et al





et al



lt






80




1

pp 77ndash90


et al




Weight gain charts







lt


gt


ge



81



1

pp 77ndash90



et al


et al



et al


et al



gt


et al





82




1

pp 77ndash90



et al





Fig 1


Fig 2




174

172

170

168

166

164

162

160

158

156

154

152

150

148

146

144

142

140

100

95

90

85

80

75

70

65

6060

55

50

45

40

35

3070

75

80

85

90

95

100

105

110

115

120

125

130

135

Height(cm)

Weight(kg)



83



1

pp 77ndash90



plusmn

383 g(Mean

plusmn

SD) and 3450

plusmn

363 g (Mean

plusmn


plusmn

398 g (Mean

plusmn


lt

3000 g or

ge



et al


Fig 3


et al


Table 1


et al

1999)

BMI PSW

Week 10Underweight

lt

2115

lt


gt

2673

gt

120Week 40

Underweight

lt

2655

lt


gt

3003

gt

1348


Table 2


lt


et al

1999) (

n

=

1745 women)

OR CI 95



Table 3


ge


et al

1999) (

n

=

1745 women)

OR CI 95



84




1

pp 77ndash90


et al








plusmn

61 kg(mean

plusmn


countries (Schieve

et al


plusmn

52 kg(mean

plusmn



plusmn






85



1

pp 77ndash90


et al



































Conclusions







References





































































80




1

pp 77ndash90


et al




Weight gain charts







lt


gt


ge



81



1

pp 77ndash90



et al


et al



et al


et al



gt


et al





82




1

pp 77ndash90



et al





Fig 1


Fig 2




174

172

170

168

166

164

162

160

158

156

154

152

150

148

146

144

142

140

100

95

90

85

80

75

70

65

6060

55

50

45

40

35

3070

75

80

85

90

95

100

105

110

115

120

125

130

135

Height(cm)

Weight(kg)



83



1

pp 77ndash90



plusmn

383 g(Mean

plusmn

SD) and 3450

plusmn

363 g (Mean

plusmn


plusmn

398 g (Mean

plusmn


lt

3000 g or

ge



et al


Fig 3


et al


Table 1


et al

1999)

BMI PSW

Week 10Underweight

lt

2115

lt


gt

2673

gt

120Week 40

Underweight

lt

2655

lt


gt

3003

gt

1348


Table 2


lt


et al

1999) (

n

=

1745 women)

OR CI 95



Table 3


ge


et al

1999) (

n

=

1745 women)

OR CI 95



84




1

pp 77ndash90


et al








plusmn

61 kg(mean

plusmn


countries (Schieve

et al


plusmn

52 kg(mean

plusmn



plusmn






85



1

pp 77ndash90


et al



































Conclusions







References






































































81



1

pp 77ndash90



et al


et al



et al


et al



gt


et al





82




1

pp 77ndash90



et al





Fig 1


Fig 2




174

172

170

168

166

164

162

160

158

156

154

152

150

148

146

144

142

140

100

95

90

85

80

75

70

65

6060

55

50

45

40

35

3070

75

80

85

90

95

100

105

110

115

120

125

130

135

Height(cm)

Weight(kg)



83



1

pp 77ndash90



plusmn

383 g(Mean

plusmn

SD) and 3450

plusmn

363 g (Mean

plusmn


plusmn

398 g (Mean

plusmn


lt

3000 g or

ge



et al


Fig 3


et al


Table 1


et al

1999)

BMI PSW

Week 10Underweight

lt

2115

lt


gt

2673

gt

120Week 40

Underweight

lt

2655

lt


gt

3003

gt

1348


Table 2


lt


et al

1999) (

n

=

1745 women)

OR CI 95



Table 3


ge


et al

1999) (

n

=

1745 women)

OR CI 95



84




1

pp 77ndash90


et al








plusmn

61 kg(mean

plusmn


countries (Schieve

et al


plusmn

52 kg(mean

plusmn



plusmn






85



1

pp 77ndash90


et al



































Conclusions







References





































































82




1

pp 77ndash90



et al





Fig 1


Fig 2




174

172

170

168

166

164

162

160

158

156

154

152

150

148

146

144

142

140

100

95

90

85

80

75

70

65

6060

55

50

45

40

35

3070

75

80

85

90

95

100

105

110

115

120

125

130

135

Height(cm)

Weight(kg)



83



1

pp 77ndash90



plusmn

383 g(Mean

plusmn

SD) and 3450

plusmn

363 g (Mean

plusmn


plusmn

398 g (Mean

plusmn


lt

3000 g or

ge



et al


Fig 3


et al


Table 1


et al

1999)

BMI PSW

Week 10Underweight

lt

2115

lt


gt

2673

gt

120Week 40

Underweight

lt

2655

lt


gt

3003

gt

1348


Table 2


lt


et al

1999) (

n

=

1745 women)

OR CI 95



Table 3


ge


et al

1999) (

n

=

1745 women)

OR CI 95



84




1

pp 77ndash90


et al








plusmn

61 kg(mean

plusmn


countries (Schieve

et al


plusmn

52 kg(mean

plusmn



plusmn






85



1

pp 77ndash90


et al



































Conclusions







References






































































83



1

pp 77ndash90



plusmn

383 g(Mean

plusmn

SD) and 3450

plusmn

363 g (Mean

plusmn


plusmn

398 g (Mean

plusmn


lt

3000 g or

ge



et al


Fig 3


et al


Table 1


et al

1999)

BMI PSW

Week 10Underweight

lt

2115

lt


gt

2673

gt

120Week 40

Underweight

lt

2655

lt


gt

3003

gt

1348


Table 2


lt


et al

1999) (

n

=

1745 women)

OR CI 95



Table 3


ge


et al

1999) (

n

=

1745 women)

OR CI 95



84




1

pp 77ndash90


et al








plusmn

61 kg(mean

plusmn


countries (Schieve

et al


plusmn

52 kg(mean

plusmn



plusmn






85



1

pp 77ndash90


et al



































Conclusions







References





































































84




1

pp 77ndash90


et al








plusmn

61 kg(mean

plusmn


countries (Schieve

et al


plusmn

52 kg(mean

plusmn



plusmn






85



1

pp 77ndash90


et al



































Conclusions







References






































































85



1

pp 77ndash90


et al



































Conclusions







References






























































































Conclusions







References




















































































Conclusions







References









































































Conclusions







References























































































































































Documents

A weight gain chart for pregnant women designed in Chile