Amer J Perinatol
DOI: 10.1055/s-0037-1607042
Original Article
Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Risk of Expectant Management and Optimal Timing of Delivery in Low-Risk Term Pregnancies: A Population-Based Study

Gustavo Vilchez1, Sarah Nazeer1, Komal Kumar1, Morgan Warren1, Jing Dai2, Robert J. Sokol2
  • 1Department of Obstetrics and Gynecology, University of Missouri-Kansas City School of Medicine, Kansas City, Missouri
  • 2Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, Michigan
Further Information

Publication History

28 May 2017

22 August 2017

Publication Date:
22 September 2017 (eFirst)


Objective The benefits of the 39-week rule have been questioned and concerns of increased stillbirth after adoption of this rule have been raised. Whether expectant management risks outweigh the benefits of awaiting 39 weeks has not been studied. We analyze the risks of expectant management at term and the optimal timing for delivery.

Study Design All U.S. nonanomalous singleton term deliveries in 2013 were selected, excluding diabetes/hypertension, and low birth weight. Maternal/neonatal complications and stillbirth/infant death were compared among expectant management versus deliveries at each term gestational age. Logistic regression was used to calculate adjust odds ratios of complications according to delivery plan at each gestational age.

Results From ∼3 million deliveries, maternal complications during expectant management were lower at early term, and became higher at 39 weeks, relative risk [RR] (95% confidence interval [CI]) = 1.18 (1.16–1.19). Neonatal complications during expectant management were lower during early term, and became higher at ≥39 weeks, RR (95% CI) = 1.09 (1.08–1.09). The risk of perinatal mortality in the expectant management group was lower during early term, and became higher at ≥39 weeks, 18.93 (17.83–20.10) versus 17.37 (16.61–18.16), p = 0.010.

Conclusion Complications during expectant management occurring while awaiting full term do not outweigh the benefits of better outcomes from reaching 39 weeks. However, extending beyond 39 weeks may put these pregnancies at an increased risk.