Management of Pregnancy at 40 Weeks Gestation
Induction of labor at 40 weeks gestation is recommended as the best management approach for a pregnancy at 40 weeks to reduce perinatal complications without increasing cesarean delivery rates. 1
Evidence for Induction at 40 Weeks
- The American College of Obstetricians and Gynecologists recommends elective induction of labor at 39 weeks 0-4 days as a reasonable option for low-risk nulliparous women with reliable dating 1
- Elective induction of labor at 39 weeks is associated with reduced cesarean delivery rates (18.6% vs 22.2%) compared to expectant management 1
- Induction of labor at term is associated with fewer perinatal deaths compared to expectant management (RR 0.31,95% CI 0.15 to 0.64) 2
- There is a clear reduction in stillbirth rates with a policy of labor induction at or beyond 37 weeks compared with expectant management (RR 0.30,95% CI 0.12 to 0.75) 2
- The risk of stillbirth increases from 39 weeks onwards with a sharp rise after 40 weeks of gestation 3
Benefits of Induction at 40 Weeks
- Lower rates of neonatal intensive care unit (NICU) admission (RR 0.88,95% CI 0.80 to 0.96) with induction compared to expectant management 2
- Probably fewer babies with Apgar scores less than seven at five minutes in induction groups compared with expectant management (RR 0.73,95% CI 0.56 to 0.96) 2
- Reduced incidence of hypertensive disorders of pregnancy (9.1% vs 14.1%) with elective induction compared to expectant management 1
- Induction of labor at 40 weeks is associated with fewer cesarean sections compared with expectant management (RR 0.90,95% CI 0.85 to 0.95) 2
Risks of Expectant Management Beyond 40 Weeks
- Perinatal mortality increases as gestation continues beyond term (around 40 weeks' gestation) 2
- The risk of stillbirth at 41 weeks of pregnancy is 2 to 3 per 1000 deliveries 4
- Labor complications increase from 40 to 42 weeks, including length of labor, prolonged second stage, forceps use, and cesarean delivery 5
- Neonatal complications such as meconium aspiration syndrome increase with advancing gestational age beyond 40 weeks 4
Special Considerations
- For pregnancies with fetal growth restriction (FGR) and normal Doppler studies, delivery is recommended at 38-39 weeks gestation 6
- For FGR with decreased diastolic flow, delivery is recommended at 37 weeks gestation 6
- For women with cardiac disease, induction of labor at 40 weeks is recommended to avoid complications associated with prolonged pregnancy 7
- In women at high risk for valve thrombosis requiring anticoagulation, planned delivery may be necessary to minimize the period off anticoagulation 7
Mode of Delivery Considerations
- Vaginal delivery is recommended for most women, with cesarean section reserved for obstetric indications 7
- Epidural anesthesia is recommended to avoid the stress of pain during delivery 7
- For high-risk patients with cardiac disease, elective cesarean section should be considered to maintain more stable hemodynamics 7
Practical Approach to Management
- Confirm accurate dating of pregnancy before making decisions about induction 1
- Discuss the benefits and risks of induction versus expectant management with the patient 1
- If induction is chosen, use appropriate cervical ripening methods for unfavorable cervix 1
- Allow adequate time for labor progress during the induction process 1
- Monitor fetal well-being throughout labor with appropriate fetal surveillance 7
By implementing induction of labor at 40 weeks gestation, clinicians can reduce the risk of adverse perinatal outcomes while maintaining favorable maternal outcomes.