Does stage of labor at time of cesarean delivery affect risk of subsequent preterm birth? - 29/10/14

Doi : 10.1016/j.ajog.2014.09.035

Lisa D. Levine, MD, MSCE ^a,^⁎ , Mary D. Sammel, ScD ^b, Adi Hirshberg, MD ^a, Michal A. Elovitz, MD ^a, Sindhu K. Srinivas, MD, MSCE ^a
^a Maternal and Child Health Research Department, Department of Obstetrics and Gynecology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
^b Department of Biostatistics and Epidemiology, Center for Clinical Epidemiology and Biostatistics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA

^∗Corresponding author: Lisa D. Levine MD, MSCE.

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Abstract

Objective

The effect of a cesarean delivery in different stages of labor on spontaneous preterm birth (sPTB) in a subsequent pregnancy has not been studied extensively. The objective of the study was to evaluate the risk of subsequent sPTB after a first-stage or second-stage cesarean delivery compared with a vaginal delivery.

Study Design

This was a planned secondary analysis of a large retrospective cohort study of women with 2 consecutive deliveries from 2005-2010. Women with a previous sPTB were excluded. First-stage (<10 cm) and second-stage (≥10 cm) cesarean deliveries were compared with vaginal deliveries. Data were obtained through chart abstraction. The primary outcome was sPTB (<37 wk) in a subsequent pregnancy. Categoric variables were compared with the use of χ² analyses, and logistic regression was used to calculate odds and control for confounders.

Results

Eight hundred eighty-seven women were included (721 vaginal deliveries; 129 first-stage and 37 second-stage cesarean deliveries). The sPTB rate varied between groups (7.8%, 2.3%, and 13.5%, respectively; P = .03). When compared with women with a vaginal delivery, women with a first-stage cesarean delivery had a decreased risk of sPTB, which remained after adjustment for confounders (adjusted odds ratio, 0.30; 95% confidence interval, 0.09–0.99; P = .049). There was a nonsignificant increase in odds of sPTB after a second-stage cesarean delivery compared with a vaginal delivery (adjusted odds ratio, 2.4; 95% confidence interval, 0.77–7.43; P = .13). Women with a second-stage cesarean delivery had a 6-fold higher odds of sPTB compared with women with a first-stage cesarean delivery, which remained after adjustment for confounders (adjusted odds ratio, 5.8; 95% confidence interval, 1.08–30.8; P = .04).

Conclusion

Women with a full-term second-stage cesarean delivery have a significantly higher than expected rate of subsequent sPTB (13.5%) compared with both the overall national sPTB rate (7-8%) and to a first-stage cesarean delivery (2.3%). As the cesarean delivery rate continues to rise, this potential impact on pregnancy outcomes cannot be ignored.

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Key words : cesarean delivery, preterm birth, second stage of labor

Plan

Materials and Methods

	This study was supported in part by National Institute of Health Reproductive Epidemiology Training Grant number 5T32HD007440-15 and a career development award in Women’s Reproductive Health Research, K12-HD001265-14.
	M.D.S. is a statistical consultant for the American Journal of Obstetrics & Gynecology. The authors report no conflict of interest.
	Cite this article as: Levine LD, Sammel MD, Hirshberg A, et al. Does stage of labor at time of cesarean delivery affect risk of subsequent preterm birth? Am J Obstet Gynecol 2014;211:••••.