What is the management approach for a pregnancy beyond 39 weeks?

Management of Pregnancy Beyond 39 Weeks

For low-risk nulliparous women at 39 weeks gestation, elective induction of labor is reasonable and associated with lower rates of cesarean delivery and hypertensive disorders compared to expectant management. 1

Management Options at 39 Weeks

• Elective induction of labor at 39 weeks 0-4 days is a reasonable option for low-risk nulliparous women with reliable dating 1
• Expectant management until spontaneous labor or until a medical indication for delivery arises is also reasonable 1
• Both approaches have similar neonatal outcomes, with no statistically significant difference in the composite of perinatal death or severe neonatal morbidity 1

Benefits of Elective Induction at 39 Weeks

• Reduced cesarean delivery rates (18.6% vs 22.2%) compared to expectant management 1
• Lower incidence of hypertensive disorders of pregnancy (9.1% vs 14.1%) 1
• Reduced meconium-stained amniotic fluid (3.2% vs 19.4%) 2
• Decreased need for fetal resuscitation (4.8% vs 16.7%) 2

Timing of Delivery Recommendations

• For low-risk nulliparous women: Consider elective induction at 39 weeks 0 days to 39 weeks 4 days 1
• For women with preeclampsia: Deliver at ≥37 weeks gestation 1
• For late-term pregnancies (41 weeks 0 days to 41 weeks 6 days): Induction of labor is recommended to reduce perinatal mortality 3
• For post-term pregnancies (≥42 weeks): Delivery is strongly recommended due to exponentially increased risks of fetal mortality and stillbirth 3, 4

Protocol for Elective Induction at 39 Weeks

1. Patient Selection:

   • Confirm eligibility criteria similar to ARRIVE trial participants 1
   • Ensure reliable dating with early ultrasound confirmation 1
   • Nulliparous women with singleton pregnancy, cephalic presentation, no contraindications to vaginal delivery 1

2. Induction Process:

   • For unfavorable cervix (modified Bishop score <5), use cervical ripening agent 1
   • Allow adequate time for labor progress (at least 12 hours after completion of cervical ripening, rupture of membranes, and uterine stimulation) before considering failed induction 1

Special Considerations

• For fetal growth restriction (FGR) with normal Doppler: Delivery recommended at 38-39 weeks 5
• For FGR with decreased diastolic flow: Delivery at 37 weeks 5
• For FGR with absent end-diastolic velocity: Delivery at 33-34 weeks 5
• For FGR with reversed end-diastolic velocity: Delivery at 30-32 weeks 5

Monitoring During Expectant Management

• For pregnancies ≥41 weeks: Antepartum fetal monitoring is recommended to mitigate risks of perinatal morbidity and mortality 3
• For FGR with normal umbilical artery Doppler: Serial umbilical artery Doppler assessment every 2 weeks 5

Important Caveats

• The number needed to treat (NNT) to prevent one cesarean delivery with elective induction at 39 weeks is 28 1
• These recommendations apply specifically to low-risk nulliparous women; it is unknown if findings can be extrapolated to multiparous women 1
• Women with medical or obstetric conditions requiring induction should be delivered according to condition-specific guidelines 1
• Shared decision-making is essential, as some women may prefer elective induction while others may prefer expectant management 1