Maternal and obstetric complications of pregnancy are associated with increasing gestational age at term

Caughey, Aaron B. MD, MPP, MPH, PhD
Stotland, Naomi E. MD
Washington, A. Eugene MD, MSc
Escobar, Gabriel J. MD

Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, School of Medicine, San Francisco, CA (Drs Caughey, Stotland, and Washington), and the Division of Research, Perinatal Research Unit, Kaiser Permanente, Oakland, CA (Dr Escobar).

Drs Caughey and Stotland are Women's Reproductive Health Research Scholars, sponsored by the National Institute of Child Health and Human Development, Grant # HD01262. This project was supported by the Agency for Healthcare Research and Quality (grant number P01 HS010856, “Promoting Effective Communication and Decision Making for Diverse Populations”). The contents of this article are solely the responsibility of the authors and do not necessarily represent the official views of the AHRQ.

Reprints not available from the authors.

Received Apr. 14, 2006; revised June 19, 2006; accepted Aug. 30, 2006.

American Journal of Obstetrics and Gynecology 196(2):p 155e1-155e6, February 2007.

Objective

We sought to estimate when rates of maternal pregnancy complications increase beyond 37 weeks of gestation.

Study design

We designed a retrospective cohort study of all low-risk women delivered beyond 37 weeks' gestational age from 1995 to 1999 within a mature managed care organization. Rates of mode of delivery and maternal complications of labor and delivery were examined by gestational age with both bivariate and multivariable analyses.

Results

We found that, among the 119,254 women who delivered at 37 completed weeks and beyond, the rates of operative vaginal delivery (OR 1.15, 95% CI 1.09, 1.22), 3rd- or 4th-degree perineal laceration (OR 1.15, 95% CI 1.06, 1.24), and chorioamnionitis (OR 1.32, 95% CI 1.21, 1.44) all increased at 40 weeks as compared to 39 weeks of gestation (P < .001), and rates of postpartum hemorrhage (OR 1.21, 95% CI (1.10, 1.32), endomyometritis (OR 1.46, 95% CI 1.14, 1.87), and primary cesarean delivery (1.28, 95% CI 1.20, 1.36) increased at 41 weeks of gestation (P < .001). The cesarean indications of nonreassuring fetal heart rate (OR 1.81, 95% CI 1.49, 2.19) and cephalo-pelvic disproportion (OR 1.64, 95% CI 1.40, 1.94) increased at 40 weeks of gestation (P < .001).

Conclusion

We found that the risk of maternal peripartum complications increase as pregnancy progresses beyond 40 weeks of gestation. Management of pregnancies that progress past their EDC should include counseling regarding the risks of increasing gestational age.