The Value of a Developmental History

Develop. Med. Child Neurol. 1978,20, 442-452

The Value of a Developmental History Hilarg Hart Martin Bax Sue Jenkins

Introduction Developmental history-taking normally

forms part of developmental assessment. Many paediatricians stress the value of the child’s early milestones, both as prognostic indicators and to give a picture of the rate of development during a period when the child may not have been under regular medical surveillance. Certain milestones are frequently enquired after, and Illing- worth (1972) describes a group of ‘essential milestones’ as being particularly valuable in developmental diagnosis.

Milestones are not usually recorded at the time of achievement, therefore the doctor has to rely on the mother’s memory of past events. However, a few studies of paediatric anamnesis have been carried out which demonstrate considerable inaccuracies of mothers’ memories, increasing with lapse of time. Donoghue and Shakespeare (1967) conclude that although developmental history-taking is a rough and ready way of finding out about a child’s development, it is never- theless a worthwhile exercise. Walking has been studied most often and is gener- ally well remembered, whereas sitting is less well recalled. Pyles et al. (1935), Mednick and Shaffer (1963), Donoghue and Shakespeare (1967) and Neligan and Prudham (1969) found close agree-

ment on age of walking when comparing near-contemporary data with interviews when children were aged between 21 months and nine years. McGraw and Molloy (1941), however, found an average discrepancy of three to five months when mothers were interviewed when the child was 21 months old. Interestingly, Neligan and Prudham found that mothers of two groups of abnormal children, those with an IQ of less than 85 and those with poor speech, were less accurate in their recall of walking than were mothers of normal children. Most studies also show that mothers characteristically underestimate the age of achieving milestones.

Donoghueand Shakespeare( 1967)found mothers’ recall of the age of saying first words to be unreliable, but there has been little investigation of recall of speech milestones and of smiling. As these milestones continue to be enquired after at considerable intervals after achievement, both for clinical purposes and in epidemio- logical studies, their reliability merits further examination. This study looks at mothers’ memories of the onset of smiling, sitting, walking, naming persons, naming objects, and talking in sentences when interviewed repeatedly when their child was between the ages of six weeks and 48 years. It compares the same mothers’

Currr.spo~rdrnce tu Dr. Martin Bax, Thomas Coram Research Unit, 41 Brunswick Square, London W C ~ N IAZ.

442

HILARY HART MARTIN BAX SUE JENKINS

replies to the same questions repeated after various intervals of time, and looks at the length of time mothers’ memories remain accurate enough to be clinically valuable.

Method The sample of children consisted of all

those under five years of age living in two geographically defined areas in north London and who are taking part in a longitudinal study of the health and development of pre-school children. 20 per cent of the mothers were unmarried and the social class of the remainder, based on the husband’s occupation, comprised 34 per cent non-manual workers and 46 per cent manual workers. 71 per cent of mothers had been born in Great Britain and Ireland, 12 per cent in the West Indies, 2 per cent in India and 16 per cent elsewhere (mainly other European coun- tries and Africa). The results presented here are from all the children living in the areas at the start of the study, who were recruited at all ages from 0-5 years, plus those who have since moved into the area and all new births.

The children received medical and developmental examinations when they reached the ages of six weeks, six months, one year, 18 months, two years, three years and 44 years. At each age the mother was asked by the doctor when the child had reached certain milestones. Smiling was asked at every age, sitting at six months and one year, walking and naming people and objects at one year and after, and sentences at 18 months and after. The meaning of each milestone was discussed by the doctors beforehand to ensure as reliable a result as possible. They were defined as follows: Smiling-smiles in response to social stimulus, e.g. mother’s face or voice (a distinction was made from a grimace or wind).

Sitting-sits without support for half a minute. Walking-walks at least five steps unaided. Names person-says ‘Mum’ or ‘Dad’ or names other person meaningfully. Names object-names one or more objects correctly. Uses sentences-puts two or three words together meaningfully.

The developmental history was taken by one of the three doctors on the research team, and to prevent biased recording at follow-up examinations the history taken on an earlier occasion was not made available.

Mothers were asked when their child had reached a milestone, although we recognise that this may be inaccurately recalled after a lapse of time. Therefore the results were analysed as to whether a child had reached a milestone by a certain age. This is likely to be more accurate than the exact date and is satisfactory for clinical purposes. When we compared mothers’ recall of a milestone on two or more occasions, the first interview was carried out near the time of achieving the milestone. We recorded whether or not the mother reported the child having achieved the milestone and this information was compared with subsequent replies. Great care was taken to explain the meaning of the milestones to each mother, and to advise her that as many people cannot remember events which occurred some time ago, if she was uncertain it was preferable to say she could not remember rather than to make a guess.

Children with definite physical or mental handicap and those more than four weeks premature were excluded from the sample. The ages of reaching milestones were recorded to the nearest week for smiling and in months for the other milestones. Replies of half a week or month were rounded upwards: for example, a reply that a child was sitting at 64 months was

443

DEVELOPMENTAL MEDICINE AND CHILD NEUROLOGY. 1978, 20

Milestone I

recorded as seven months. 426 children had a developmental

history taken at their first examination of the study (referred to as initial sample). Most of these children (excluding those who moved out of the areas) have had one or more follow-up examinations. For each milestone, results are also presented for a group of children whose mothers’ memories of the age of reaching the milestone were recorded on two or more consecutive occasions and one obser- vation was close to the time of achieving the milestone (referred to as follow-up group). The numbers in the follow-up group differ for each milestone, as a few children with incomplete observations for a particular milestone were excluded.

Age of child when history taken 6 wks 6 mths 12 mths 18 mths 2 yrs 3 yrs 43yrs

Results A developmental history was obtained

Couldn’t remember

Total

from mothers of 426 children at the start of the study. Table I shows the proportion of mothers recalling the age at which the various milestones were achieved and the age of the index child when the question was asked. Smiling was recalled by less than 60 per cent of mothers after the age of 12 months. Speech milestones were recalled by three-quarters of the mothers, but only half recalled the age of naming persons by the time the child was 44 years. Walking was the most frequently remembered item, being recalled by over 95 per cent of mothers at all ages.

We actually asked the mother at what age their baby smiled, but we have analysed the results as to whether the baby smiled before or after six weeks. In the initial sample, 86 per cent of mothers at the six-week examination reported their babies to be smiling, but only 30

- 4 13 -

126 100 30 100

TABLE I Percentage of mothers recalling each milestone (initial sample)*

Smiling Sitting Walking Names person Names objects Sentences

87 62 50 54 58 51 93 82

100 100 96 95 95 91 89 72 74 56 94 97 76 66

92 83 82 69

I Total sample I 126 30 34 36 46 76 78

* Based on all children, whether or not they had achieved the milestone.

TABLE I1 Percentage of mothers recalling smiling at six weeks (initial sample)

I 6wks 6 mths

I

.4ge of child when mother asked

No. 04 No. Smiled by 6 wks 1 108 86 9 30 I Did not smile by 6 wks 18 14 17 57


Asked at 6 mths- Yes Smiling by 6 wks No

Total CR

per cent of the group examined first at six months recalled their babies smiling at six weeks (Table 11). In the follow-up group of the same children seen at six weeks and six months, 85 per cent reported smiling at the six-week exam but only 59 per cent recalled smiling by six weeks when asked at six months (Table 111). The percentage of mothers at the six-month exam recalling smiling by six weeks was significantly higher (59 per cent) in the follow-up group than in the initial sample (30 per cent) (p <0.01). This suggests that asking mothers about their baby’s smiling at six weeks may increase the mother’s ability of recalling the milestones later.

Sixty-five per cent of mothers in the follow-up group agreed at six weeks and six months on whether their babies were smiling by six weeks (Table 111). 16 mothers (19 per cent) recalled that their child smiled after six weeks when asked at six months, although they had reported at six weeks that their child was smiling. 10 of these mothers reported smiling after eight weeks-one at 11 weeks, eight at three months and one at five months- differences which could be of clinical importance.

Of the 62 mothers who reported smiling at six weeks and remembered smiling at six months, 57 per cent agreed within one week and 73 per cent within two weeks. Of the 12 mothers who reported their babies not smiling by six weeks when

Asked at 6 wks-Smiling by 6 wks Yes No CR* Total

No. % 46 55 2 - 48 59

- 24 29 - 11 13

16 19 8 10 9 11 2 2

71 85 12 14 - 83 100

No* % No* 3

asked at six weeks, two reported smiling by six weeks when asked at six months, two could not remember and eight reported smiling between six and 12 weeks.

Frankenburg and Dodds (1967), when standardising the Denver Developmental Screening Test, found that 75 per cent of babies smiled by six weeks and 90 per cent by eight weeks. However, Soderling (1959) followed 400 infants closely during the first weeks of life and, using strict criteria for a true responsive smile, found that 60 per cent smiled by four weeks and 100 per cent by six weeks.

Our results at six weeks show an expected rate of smiling. Two-thirds of mothers remember smiling fairly accur- ately by the age of six months, but others recall the child smiling later than he did- in several cases six weeks later. Smiling is the only milestone which mothers tended to report as occurring at a later age. It would appear, therefore, that a mother’s history of late smiling is unreliable and clinically misleading when asked at six months, and less than two-thirds of mothers recall the start of smiling after this time.

Sitting The proportion of children sitting by

six months was similar when asked at six months and one year in both initial and follow-up groups (Tables IV and V). 51 per cent of mothers agreed about sitting by six months when asked again at one


Sitting by 6 mths

Couldn’t remember Not sitting by 6 mths

year, and 20 per cent couldn’t remember this detail when their child was a year old (Table V). 15 per cent reported sitting earlier at one year and 14 per cent later. Of those who could remember at both ages, 80 per cent of mothers agreed within one month and 96 per cent to within two months.

Walking In both the initial and follow-up groups

the percentages of children said to be walking by 12 months were higher when asked at 18 months than at 12 months (Tables VI and VII). Possibly some babies walked very soon after a year and mothers tended to round off the age of walking to 12 months. Inspection of the raw data confirms this: the number of children said to be walking at 12 months equalled the total said to be walking at 11 and 13 months combined. Neligan and Prudham (1969) reported similar findings.

In the initial sample the percentages of children walking by 12 months and 14 months were similar in all age-groups from

No. No. 9 30 13 38

19 63 15 44 2 7 6 18

18 months upwards, and the mean ages of walking did not differ significantly between the 18-month and two-year age- groups. This consistency was confirmed in the follow-up group. 69 per cent of mothers agreed about whether their child walked by 12 months when asked at 12 months and 18 months, but 28 per cent reported walking earlier (Table VIII). 96 per cent of mothers’ replies agreed within one month between 12 and 18 months and 83 per cent agreed between 18 months and two years.

In general, apart from a tendency to round off the age of walking to 12 months, this milestone is well remembered by nearly all mothers.

Naming Person The percentage of children remembered

as naming a person by one year was similar when asked at all ages in the initial sample, but by the age of years only half the mothers could recall when the child started naming (Table IX). In the follow- up group, the proportion of children

TABLE 1V Percentage of mothers recalling sitting by six months (initial sample)

Age of child when inother asked 6 mths 12 mths

I

I - - T o r 1 30 100 34 100 ~~

TABLE V Agreement between mothers’ reports of sitting by six months when asked at six

months and at one year (follow-up group) I I

Sitting by 6 rnths-Asked at 6 niths Yes No CR* Total

Asked at one year- Yes sitting by No 6 mths CR

Total

No. ‘/ No. No. 20 i P 10 15 - 30 46 9 14 13 20 - 22 34 7 11 6 9 - 13 20

36 56 29 44 - 65 100 I I

‘Couldn’t remember

446


Asked at 18 mths- Yes walked by 12 mths No

CR Total

TABLE VI Percentage of mothers recalling walking by 12 months and 14 months (initial sample)

Age of child when mother asked 12 mths 18 mths 2 yrs 3 yrs 43 yrs

Asked at 12 mths- Walked at 12 mrhs Yes No CR* Total

No. % No. % No. % 40 58 21 30 19 28 - 27 39 27 39 -

2 3 2 3 69 100 23 33 46 67 -

-

No. % No. % NO. % NO. % NO. % 7 21 21 58 25 54 46 60 45 58

1 W2aki-I by 12

Walked bv 14 mths

walking of those walking at time of interview

remember

Mean age of

Couldn’t

29 80 38 82 61 80 58 73

12.2 mths 12.3 mths 12.4 mths 12.6 mths SD 2.1 SD 2.5 SD 2.0 SD 3.4

2 4 4 5 4 5

Total sample 1 34 100 36 100 46 100 76 100 78 100 I TABLE VII

Age of walking in follow-up group seen at 12 months and 18 months*

Walked by 12 mths Walked by 14 mths Mean age of walking of those

walking at time of interview

Couldn’t remember

Total sample

Age of child when mother asked 12 mths 18 mths 2 yrs

No. % No. % No. % 23 33 40 58 22 61

59 85 29 80

12.4 mths 12.3 mths SD 1.8 SD 2.3

2 3 1 3

69 100 69 100 36 100

*36 of the children were also seen at age 2 years.

TABLE VIII Agreement between mothers’ reports of walking by 12 months when asked at 12 months

and 18 months

I I I *Couldn’t remember

TABLE IX Percentage of mothers recalling naming person by 12 months (initial sample)

i Age of child when mother asked

12 mths 18 mths 2 yrs 3 yrs 43 yrs

Named person by 12 mths Couldn’t remember

Total sample

No. % No. % No. % No. % No. % 22 65 17 47 28 61 47 62 36

46 I 3 9 4 11 13 28 20 26 34 44 -1 34 100 36 100 46 100 76 100 70 100 I 447


Asked at 18 mths- No names person at 12 mths Yes

CR Total

naming persons by one year was similar when asked at one year (69 per cent) and when asked again at 18 months (52 per cent). At two years, 43 per cent could not remember the age of naming (Table X).

Sixty-two per cent of mothers agreed about naming by 12 months when asked at 12 months and 18 months. 39 per cent agreed when asked at 12 months and two years, and 43 per cent couldn’t remember at two years. 55 per cent of mothers agreed within two months when asked at 12 and 18 months and 43 per cent when asked at 12 months and two years. On looking at the raw data, it was apparent that most mothers gave different replies when asked on three occasions. Only six mothers (14 per cent) said on all three occasions that they remembered naming and gave three replies which agreed within two months (Tables XI to XIII).

No. No. % No. % 18 43 4 10 - 22 52 5 12 8 19 - 1 3 31 6 14 1 2 - 7 17

29 69 13 31 - 42 100

Names Object In the initial sample, more mothers

remembered their children naming an

object by one year when asked a t two (35 per cent) and three years (30 per cent) than those actually asked at one year (15 per cent) (Table XIV).

In the follow-up group, a third of mothers could not remember the age of naming objects when asked at two years (Table XV). These were mostly mothers whose child named objects before 18 months. 53 per cent agreed about whether the child named objects by 18 months when asked at 18 months and two years. Only 14 out of 62 mothers (23 per cent) were able to give a time for naming objects on two occasions and gave replies agreeing within two months.

Sentences In the initial sample, more mothers

recalled their children as speaking in sentences by 18 months at two years (30 per cent), three years (39 per cent) and 44 years (36 per cent) than those actually asked at 18 months (17 per cent) (Table XVI).

TABLE X Percentage of mothers recalling naming person by 12 months (follow-up group)

Age of child when mother asked 12 mths 18 mths 2 yrs

No. % No. % 69 22 52 17 40 o / /O I Couldn’t remember 7 17 18 43

Naming person by 12 mths

Total sample 1 42 100 42 100 42 100 I TABLE XI

Agreement between mothers’ reports of naming person by 12 months when asked at 12 months and at 18 months

I Asked at I 2 mths-Names person by I 2 mths I Yes No CR* Total

~

*Couldn’t remember

448


Asked at 2 yrs- Yes

18 mths CR named objects by No

Total

TABLE XI1 Agreement between mothers’ reports of naming person by one year when

asked at one year and two years

No. % No. % No. % No. % 23 37 4 7 2 3 29 47

13 21 10 16 20 32 14 23 6 10

40 65 20 33 2 3 62 100

- - - - 3 5

Asked at 12 mths No CR* Total

I I *Couldn’t remember

TABLE XI11 Agreement between mothers’ reports of naming person by one year when asked at

18 months and two years ~~

I I Asked at 18 mrhs

Yes No CR* Total I- No. % No. % No. % No. % 11 26 3 7 3 7 17 40

7 17 No 2 6 14 - - CR I 1; 24 4 10 4 10 18 44

I Totai 52 13 31 7 17 42 100

*Couldn’t remember

TABLE XIV Percentage of mothers recalling naming objects by one year and by 18 months

(initial sample)

Named object by

Named object by

Couldn’t remember

12 mths

18 mths

Age of child when mother asked 12 mths 18 mths 2 yrs 3 yrs

No. % No. % No. % No. % 5 15 5 14 16 35 23 30

21 58 21 59 40 51 2 6 1 3 11 24 26 34

I To tal sample I 34 100 36 100 46 100 76 100

TABLE XV Agreement between mothers’ reports of naming objects by 18 months when asked

at 18 months and two years

I Asked at 18 mths-Named objects by 18 mths 1 Yes No CR* Total

I I *Couldn’t remember

C 449


Asked at 2 yrs - Yes sentences by 18 mths No

CR Total

More mothers in the follow-up group recalled their children as speaking in sentences by 18 months when asked at two years than when actually asked at I8 months, but 73 per cent of mothers agreed on this milestone at the two ages (Table XVII). 25 children were seen at two and three years, and only three of these were remembered as saying sentences by 18 months when asked at two years, but nine reported sentences by 18 months when asked again at three years.

In a previous study (Bax and Whitmore, unpublished), we asked mothers of school entrants to check the appropriate box (18, 21, 24, etc.. to 36 months) for when their child was speaking in sentences. Nearly all the mothers checked the 18- month box. This, together with the present evidence, suggests that mothers tend to recall their child speaking in sentences at an earlier age than they actually do.

Conclusions When taking a paediatric case-history,

No. :4 No. No. % No. % 5 7 11 16 1 2 17 25

50 73 5 7 45 66 - - 1 2 1 2

10 14 57 84 1 2 68 100 - -

the doctor must always make an assessment of whether or not a mother is a reliable historian. However, particular difficulties arise when enquiring about events in the past and we can draw several conclusions from this study which may be useful for the clinician to bear in mind.

With the exception of walking, the milestones studied were soon forgotten by many mothers. Even when mothers said they recalled the milestones, their estima- tions varied considerably when asked on different occasions. We conclude that the period of accurate recall is only a matter of months, or even weeks in some cases, thus making developmental history-taking a time-consuming and often misleading exercise. The only way to obtain an accurate history is to educate mothers about the importance of developmental events and to encourage them to record them when they occur,

In assessing a presumptively normal child, the doctor should not spend much of his valuable time collecting information

TABLE XVI Percentage of mothers recalling sentences by 18 months and two years (initial samolel

Age of child nhen inother asked 18 mths 2 yrs 3 yrs 43 yrs I--

No. y o No. "/, No. :/o No. % 14 30 30 39 28 36 36 78 51 67 40 51

8 17 12 18 24 31

Sentences by 18 mths Sentences by 2 yrs Couldn't remember 8

I_ l._ll__.

Total sample 46 100 76 100 78 100 I TABLE XVII

Agreement between mothers' reports of sentences by 18 months when asked at 18 months and two years

1 Asked at 18 tnths-Sentences by 18 mths

Yes No CR* Total I- I I

*Couldn't remember

450


about developmental milestones, but should concentrate on assessing the child’s current abilities. This does not mean, of course, that when one sees a handicapped child one should not take a developmental history. On the contrary, our experience is that when a milestone is delayed (and sometimes even when it is not) the parents

are late developers; for example, in our five-year-old school entrance examinations we ask whether he was talking in sentences by three years. We do not try and collect information about the age at which a milestone was achieved in a normal child because, as this paper demonstrates, such information is likely to be unreliable.

are almost invariably concerned: Thus with Our with speech and language delay (Bax and Hart 1976, 1978), all the mothers said they were worried about this aspect of the child’s development, and some mothers of 18-month-old children also expressed concern about their child because they felt the child should be speaking in sentences. In seeing children for the first tirne for routine examinations, therefore, we now attempt to identify children who

Acknowledgements: We acknowledge the help of our colleagues in the Thomas Coram Research Unit, particularly Professor Jack Tizard and Ian Plewis. We thank the Camden, Kensington and Chelsea, and Westminster Area Health Authorities for their help and co-operation. Our work is supported by a grant from the Department of Health and Social Services.

AUTHORS’ APPOINTMENTS

Dr. Hilary Hart, Dr. Martin Bax and Dr. Sue Jenkins are Research Community Paediatricians at the Thomas Coram Research Unit, 41 Brunswick Square, London WClN 1AZ.

SUMMARY Mothers taking part in a population study of child health reported the ages at which

various milestones in their children were reached. The proportion of mothers able to recall milestones decreased with increasing time from the developmental event. Walking was the best recalled milestone and smiling the least often remembered. When comparing mothers’ memories of milestones on follow-up interviews there were considerable discrepancies : smiling was remembered as occurring later than previously reported and all other milestones tended to be reported as occurring earlier. It is concluded that routine developmental history-taking is likely to be inaccurate and clinically misleading.

d S U M E Recueil de I’historique du ddveloppement

Des mbres participant B une Ctude sur la santC de l’enfant ont indiquC les iiges auxquels les repbres variCs du dCveloppement de leurs enfants ttaient atteints. La proportion des mbres capables de se rappeler ces repbres dtcroit en fonction du temps passt depuis l’avbne- ment du dtveloppement. La marche apparait le repbre le mieux indiquk et le souvenir le plus souvent oublit. Quand la mkmoire des mbres sur ces repbres a pu &re comparke avec les donnCes d’interrogatoire de surveillance, des difftrences considhables sont apparues : le souvenir est situt plus tardivement que prtctdemment indiqut et tous les autres rephes plus prkcodment. On peut conclure que le recueil de routine de l’historique de dtveloppement est peu prtcis et conduit B des erreurs cliniques.

ZUS AMMENFASflUNG Aufnehmen von Entwicklungsanamnesen

451

Im Rahmen einer allgemeinen Studie ober die Gesundheit des Kindes berichteten

DEVELOPMENTAL MEDICINE AND CHILD NEUROLOGY. 1978,20

Mutter mit welchem Alter ihre Kinder die verschiedenen Entwicklungsstadien erreicht hatten. Die Zahl der Mutter, die sich genau an die einzelnen Entwicklungsstadien erinnern konnten, nahm mit zunehmendem Abstand von dem Entwicklungsgeschehen ab. Die meisten konnten sich an den Beginn des Laufens erinnern und die wenigsten an das erste Lacheln. Verglich man die Angaben der Mutter bei verschiedenen Befragungen, so ergaben sich erhebliche Abweichungen : das Lacheln war spater als zunachst angegeben, wahrend alle anderen Entwicklundsphasen eher fiuher waren. Daraus ergibt sich die Schlussfolgerung, dass man bei einer Routineaufnahme der Entwicklungsanamnese sehr wahrscheinlich ungenaue und klinisch irrefuhrende Angaben erhalt.

RESUMEN Historia del desarrollo

Las madres que tomaban parte en un estudio de la poblacion sobre salud mental apor- taron las edades en las cuales sus nifios habian conseguido diversas etapas importantes en su desarrollo. La proporcion de madres capaces de recordar estas etapas disminuian a medida que aumentaba el tiempo transcurrido desde el acontecimiento. El inicio de la deambulacion fue el estadio mejor recordado y la sonrisa el menos. A1 comparar las memorias de acontecimientos pasados de diversas madres en entrevistas posteriores hub0 discrepancias considerables. Asi, la sonrisa se record6 como habiendo ocurrido mas tarde de la fecha que primeramente se habia dicho y todos 10s otros estadios tendian a ser recor- dados como habiendo ocurrido mas pronto. Se concluye que el escribir la historia del desarrollo de un niiio de forma rutinaria puede dar resultados inexactos y clinicamente puede conducir a error.

REFERENCES Bax, M., Hart, H. (1976) ‘The health needs of pre-school children.’ Archives of Disease in Childhood, 51,

848-852. - __ Jenkins, S. (1978) ‘The reliability of assessment of speech and language in the pre-school child.’

Donoghue, E. C., Shakespeare, R. A. (1967) ‘The reliability of paediatric case history milestones.’ Develop-

Frankenburg, W. K., Dodds, J. B. (1967) ‘The Denver Developmental Screening Test.’ Journal of’Pediatrics,

Illingworth, R . S. (1972) The Developnient of rhe Infant and Young Child, Normal and Abnormal. Edinburgh:

Neligan, G., Prudham, D. (1969) ’Norms for four standard developmental milestones by sex, social class

McGraw, M. B., Molloy. L. €3. (1941) ‘The pediatric anamnesis: inaccuracies in eliciting developmental

Mednick. S. A., Shaffer, J. B. P. (1963) ‘Mothers‘ retrospective reports in child rearing research.’ American

(Zn press. )

mental Medicine and Child Neurology, 9, 64-69.

71, 181--191.

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and place in family.’ Developmenral Medicine and Child Neurology, 11, 41 3-422.

data.’ Child Developnient, 12, 255.

Journal of Orrhoosvchiatrv. 33. 457-461. Pyles, M. K , Stoli, H. R. , McFarlane, J. W. (1935) ’The accuracy of mothers reports on birth and develop-

Soderling, B. (1959) ‘The first smile: a developmental study.’ Acta Paedratrica (Uppsalu), 48, (Suppl. 117), mental data.’ Child Developnient, 6, 165.

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Documents

The Value of a Developmental History