Timing of Elective Cesarean Section
Elective cesarean sections should be performed at 39 weeks of gestation to optimize maternal and neonatal outcomes, as this timing minimizes neonatal respiratory morbidity while balancing maternal risks. 1, 2
Optimal Timing Based on Evidence
- Elective cesarean delivery at 39 weeks gestation is the recommended standard to minimize prematurity-related neonatal complications 3
- Performing elective cesarean sections before 39 weeks is associated with increased risk of neonatal respiratory morbidity and NICU admissions 2
- For women with two prior cesarean deliveries, elective delivery at 38 0/7 to 38 6/7 weeks may represent an acceptable balance between neonatal and maternal risks while decreasing the likelihood of unplanned cesarean delivery 4
- For women with three or more prior cesareans, 39 weeks remains the optimal timing with the lowest NICU admission rates (10% vs 18-20% for earlier deliveries) 5
Rationale for 39-Week Recommendation
- Neonatal outcomes are significantly better with delivery at 39 weeks compared to 38 weeks, with lower rates of:
- Composite neonatal morbidity
- Respiratory morbidity
- NICU admissions 2
- The American College of Obstetricians and Gynecologists recommends against elective deliveries before 39 weeks to minimize prematurity-related complications 3
- Waiting until 39 weeks reduces the risk of iatrogenic prematurity and its associated complications 1
Special Circumstances
For women with ≥2 previous cesarean deliveries:
- Elective delivery at 39 0/7 to 39 6/7 weeks is associated with decreased risk of adverse maternal outcomes compared to expectant management (adjusted risk ratio 0.51; 95% CI 0.29-0.91) 4
- However, the risk of unplanned cesarean delivery increases significantly with advancing gestational age (6.5% before 38 weeks, 21.7% before 39 weeks, and 32.6% before 40 weeks) 4
For HIV-infected women requiring cesarean delivery to prevent mother-to-child transmission:
- Elective cesarean delivery is recommended at 38 completed weeks of gestation (rather than 39 weeks) to reduce the likelihood of onset of labor or rupture of membranes before delivery 1
Risks of Earlier Delivery
Elective cesarean delivery at 38 weeks (compared to 39 weeks) is associated with:
Elective cesarean delivery at 37 weeks significantly increases the incidence of adverse neonatal outcomes compared to expectant management (adjusted risk ratio 1.68; 95% CI 1.39-2.01) 4
Benefits of 39-Week Timing
- Reduced risk of stillbirth compared to expectant management beyond 39 weeks (potentially preventing up to 2 fetal deaths per 1000 living fetuses) 6
- Optimal fetal lung maturity, reducing respiratory complications 2
- Decreased risk of neonatal encephalopathy compared to vaginal delivery 6
- Maternal outcomes are generally similar between elective cesarean delivery at 38 or 39 weeks 2
Implementation Considerations
- Accurate dating is critical to avoid iatrogenic early term or preterm delivery 1
- Early ultrasonography for dating confirmation is essential (before 21 weeks for women with certain last menstrual period, first trimester ultrasound for uncertain dating) 1
- Shared decision-making is important when counseling women about timing of elective cesarean section 1
Common Pitfalls to Avoid
- Scheduling elective cesarean delivery before 39 weeks without medical indication increases neonatal morbidity 3, 2
- Failing to consider specific maternal conditions that might warrant earlier delivery (e.g., HIV infection) 1
- Inadequate confirmation of gestational age before scheduling elective cesarean section 1
- Not accounting for the increased risk of unplanned cesarean delivery with advancing gestational age in women with multiple prior cesarean deliveries 4