preterm labor gotsch

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/


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