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7/29/2019 Preterm Labor Gotsch
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Preterm Labor and
BirthPatricia B. Gotsch M.D.
St. Lukes Family Medicine ResidencyBethlehem PA
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Objectives
Define preterm labor
Discuss trends in epidemiology
Review risk factors Discuss diagnosis, treatment, and prevention
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Preterm Birth
Term pregnancy - 37 to 42 weeks gestation
12.5 % of deliveries/yr are preterm
About 500,000 71.2% 34-36 weeks
13% 32-33 weeks
10% 28-31 weeks 6%
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PTB increased 20% from 1990 to 2006
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Survival in Premature Infants
26 wks80%
27 wks90%
28-31 wks90 to 95%
32-33 wks95%
34-36 wksapproaches
term survival rates
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Complications of Prematurity
RDS
IVH
Feeding difficulties/NEC
Apnea
PDA
Infection
Jaundice
Hypothermia
Neurobehavioral
ROP
Anemia
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Preterm Birth
Spontaneous preterm labor 30-50%
Multiple gestation 10-30%
PPROM 5-40% Preeclampsia/eclampsia 12%
Antepartum bleeding 6-9%
Fetal growth restriction 2-4% Other 8-9%
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Pathogenesis
Premature activation of maternal or fetal HPA
axis
Decidual hemorrhage
Inflammation/infection
Pathological uterine distention
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Risk Factors for PTD
Previous PTB
Multiple gestation
Polyhydramnios
Uterine anomalies
Infection
Placental pathology
Smoking
Substance abuse
Maternal age extremes
Anemia
Low BMI
Hx cervical surgery
Hx 2nd TM loss
Severe stressors
Short interpregnancyinterval
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The Challenge: Identification
Labor = regular, painful uterine contractions
that produce cervical dilation and/or effacement
Uterine contractions are seen in normal
pregnancies at early gestational ages
Up to 50% of women hospitalized for PTL go
on to deliver at term
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Sonographic Cervical Length
10th% = 25mm (20 to 30
wks gestation)
80-100% of women who
deliver early have cervix
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Fetal Fibronectin
99% negative predictive
value for delivery within
2 wks
Positive predictive valueworse, about 30%
22 to 35 weeks
Sample collection issues
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Goals of Treatment of PTL
Tocolysis often halts contractions only
temporarily
Allow 48 hr+ for steroids to be given
Allow for transport to delivery location with
NICU capability
Allow for correction of reversible causes
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Steroids
Reduce incidence of RDS, IVH, NEC, sepsis,
and mortality by about 50%
Intact membranes: 24-34 weeks GA
PPROM: 24-32 weeks GA
Betamethasone 12 mg q 24 hr x 2
Dexamethasone 6 mg q 12 hr x 4
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Tocolysis
Risk/benefit ratio for continuation of pregnancy
34 weeks
Risk/benefit ratio of various treatments
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Tocolysis
Nifedipine
Low cost
Oral
Low incidence of side effects (hypotension,
dizziness, flushing)
Often considered first line
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Tocolysis
Beta agonists (ritodrine, terbutaline) Tachycardia, hypotension, tremor, palpitations, chest discomfort,
hypokalemia, hyperglycemia
Magnesium sulfate
Nausea, flushing, fatigue, diaphoresis, loss of DTRs, respiratorydepression, cardiac arrest
Indomethacin Maternal GI SE, premature closure of ductus, oligohydramnios
Atosiban Possible increase in fetal/neonatal morbidity/mortality; not available in
US
CAUTION when combining tocolytics
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Management after Tocolysis
If maternal and fetal conditions are stable, can
be managed at home
Avoid excessive physical activity; most advocate
pelvic rest
Continued tocolytics have not shown definite
benefit
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Prevention of PTB
Reduce/eliminate risk factors, if possible
Not proven to be effective: bedrest, home
uterine monitoring, prophylactic tocolytics,
prophylactic antibiotics, abstinence
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Prevention of Preterm Birth
Supplemental progesterone
Women with previous spontaneous preterm delivery
at less than 34 weeks gestation
Weekly 17OHprogesterone IM or daily vaginalprogesterone suppositories
Start at 16-20 wks gestation, continue through 36
weeks
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References
www.cdc.gov
www.marchofdimes.com
UpToDate online Use of progesterone to reduce preterm birth.
Obstet Gynecol 2008; 112:963.
Prevention of Preterm Delivery. Simhan HN etal. N Engl J Med 2007 Aug 2; 357(5):477-87.
http://www.cdc.gov/http://www.marchofdimes.com/http://www.marchofdimes.com/http://www.cdc.gov/7/29/2019 Preterm Labor Gotsch
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