POST-TERM PREGNANCYPOST-TERM PREGNANCY
Max Mongelli
Nepean Clinical School
Department of Obstetrics and Gynecology
University of Sydney
DefinitionsDefinitions
Pregnancy has extended to or beyond 42 weeks from LMP
“Post-dates” applies to pregnancy over 40 and less than 42 weeks
Critically dependent on accurate pregnancy dating
PrevalencePrevalence
Prevalence of post-term pregnancy highly dependent on local policies for induction. preterm delivery rates, complicated pregnancy rates
In the USA about 6% of pregnancies are postterm
Using 1st trimester scans for dating results in only 2% of pregnancies going postterm
Risk FactorsRisk Factors
PrimigravidityPrevious post-term pregnancyGenetic factorsMale fetusMaternal obesityFetal anencephaly
Risks to the FetusRisks to the Fetus
Doubling of perinatal mortalityAsphyxia, meconium aspiration,
intrauterine sepsisFetal macrosomiaFetal dysmaturity syndrome
Risks to the MotherRisks to the Mother
Increased risk of labor abnormalitiesThird and fourth degree perineal tearsIncreased risk of cesarean delivery
ManagementManagement
Induction of laborMembrane sweepingConservative management
Induction of LaborInduction of Labor
This is the preferred course of managementMost units induce labor from 41 weeks
onwardsStrong evidence from meta-analysis to
support reduced perinatal mortality, morbidity and cesarean section rates
Shown to be cost-effective
Membrane SweepingMembrane Sweeping
Membrane sweeping (or “stripping”) may be used to prevent post-term pregnancy
Reduces the percentage of patients going postterm from 41% to 23%
Can be repeated if required
Conservative ManagementConservative Management
Reserved for women who decline induction or labor or have a contraindication
Optimal gestational age for beginning monitoring is unknown, usually 41-42 weeks
Monitoring should include amniotic fluid assessment, CTG’s
Immediate delivery if these become abnormal
Intrapartum ManagementIntrapartum Management
Continuous electronic fetal monitoring is required
Greater risk of fetal distress or meconium aspiration
PrognosisPrognosis
No detectable differences in children born postterm regarding IQ, physical milestones or intercurrent illnesses, when tested at 1-2 years of age.
Further readingFurther reading
Max Mongelli. Evaluation of Gestation. Medscape Emedicine.