What are the chances of a normal delivery in a low-risk pregnancy?

Chances of a Normal Delivery in a Low-Risk Pregnancy

For low-risk nulliparous women, the chance of a vaginal delivery is approximately 77-81%, with elective induction of labor at 39 weeks potentially increasing this rate compared to expectant management. 1

Factors Affecting Chances of Normal Delivery

Low-Risk Nulliparous Women

• Approximately 77.8% of low-risk nulliparous women who undergo expectant management will have a vaginal delivery 1
• This rate increases to 81.4% for those who undergo elective induction of labor at 39 weeks of gestation 1
• The ARRIVE trial demonstrated that elective induction of labor at 39 weeks in low-risk nulliparous women reduced cesarean delivery rates compared to expectant management (18.6% vs 22.2%) 1

Timing of Delivery

• Elective induction of labor at 39 weeks (not before) is a reasonable option for low-risk nulliparous women with reliable dating 2
• Early term deliveries (37 weeks 0 days to 38 weeks 6 days) have increased risk of respiratory morbidity and should be avoided unless medically indicated 1
• Expectant management until spontaneous labor remains a reasonable approach for low-risk pregnancies 2

Medical Conditions Affecting Delivery Mode

• Certain conditions may necessitate specific timing or mode of delivery:
  • Gestational diabetes: Delivery at 38-39 weeks depending on medication requirements 3
  • Hypertensive disorders: Earlier delivery may be indicated 1, 2
  • Cardiac conditions: May require specialized delivery planning, potentially including cesarean section 1

Factors That May Reduce Chances of Normal Delivery

• Maternal request for cesarean delivery (estimated at 2.5% of all births in the US) 4
• High-risk conditions requiring specialized management 5
• Fetal malpresentation 1
• Maternal comorbidities requiring specific interventions 1

Optimizing Chances for Normal Delivery

• Confirming accurate dating with early ultrasound is essential for appropriate delivery planning 1
• Shared decision-making between providers and patients regarding delivery options is critical 1
• For elective induction at 39 weeks, ensuring proper patient selection and following established protocols improves success rates 2
• Allowing adequate time for labor progress during induction improves chances of vaginal delivery 2

Important Considerations

• The number needed to treat with elective induction at 39 weeks to prevent one cesarean delivery is 28 1, 2
• Elective induction at 39 weeks also reduces the risk of hypertensive disorders of pregnancy (9.1% vs 14.1%) 1
• Both elective induction and expectant management have similar neonatal outcomes with no significant difference in perinatal death or severe neonatal morbidity 2
• Maternal preferences and values should be incorporated into delivery planning, as some women may prefer expectant management despite potential benefits of elective induction 1

Pitfalls to Avoid

• Performing elective induction before 39 weeks due to the increased risk of neonatal respiratory morbidity 1
• Failing to confirm accurate dating before planning elective induction 1
• Not allowing adequate time for the induction process, which may lead to unnecessary cesarean deliveries 2
• Assuming findings from nulliparous women can be extrapolated to multiparous women, as this has not been established 1