Timing of delivery and pregnancy outcomes among laboring nulliparous women

Am J Obstet Gynecol. 2012 Mar;206(3):239.e1-8. doi: 10.1016/j.ajog.2011.12.006. Epub 2011 Dec 16.


Objective: The objective of the study was to compare pregnancy outcomes by completed week of gestation after 39 weeks with outcomes at 39 weeks.

Study design: Secondary analysis of a multicenter trial of fetal pulse oximetry in spontaneously laboring or induced nulliparous women at a gestation of 36 weeks or longer. Maternal outcomes included a composite (treated uterine atony, blood transfusion, and peripartum infections) and cesarean delivery. Neonatal outcomes included a composite of death, neonatal respiratory and other morbidities, and neonatal intensive care unit admission.

Results: Among the 4086 women studied, the risks of the composite maternal outcome (P value for trend < .001), cesarean delivery (P < .001), and composite neonatal outcome (P = .047) increased with increasing gestational age from 39 to 41 or more completed weeks. Adjusted odds ratios (95% confidence interval) for 40 and 41 or more weeks, respectively, compared with 39 weeks were 1.29 (1.03-1.64) and 2.05 (1.60-2.64) for composite maternal outcome, 1.28 (1.05-1.57) and 1.75 (1.41-2.16) for cesarean delivery, and 1.25 (0.86-1.83) and 1.37 (0.90-2.09) for composite neonatal outcome.

Conclusion: Risks of maternal morbidity and cesarean delivery but not neonatal morbidity increased significantly beyond 39 weeks.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adolescent
  • Adult
  • Delivery, Obstetric*
  • Female
  • Humans
  • Infant Mortality
  • Infant, Newborn
  • Male
  • Multicenter Studies as Topic
  • Oximetry
  • Parity*
  • Pregnancy
  • Pregnancy Outcome*
  • Risk
  • Time Factors
  • Young Adult

Grant support