Low-risk pregnancy at 41 weeks: when should we induce labor?

Abstract

Objective: To study the perinatal outcome according to whether labor was induced or not, when a low-risk pregnancy reached 41 weeks of gestation. Methods: A quasi-experimental study of 11492 low-risk singleton pregnancies was designed. A total of 1,721 patients (15.0%) women met the study criteria, were informed about the risks and benefits and gave their informed consent, of whom 629 (36.5%) were planned for induction soon after the 41 weeks (287–289 days). Results: An intention-to-treat analysis was performed. The proportion of small-for-gestational age babies was lower in the early-induced labor cohort (10.5% versus 15%; p = 0.008). This cohort showed an increased hospital stay (4.54 versus 3.80 days; p < 0.001), and a higher rate of requiring delivery by caesarean section (31.1% versus 19.8%;p < 0.001), including the need for caesarean section for failed induction (21.8% versus 11%;p < 0.001). Three stillbirths occurred in the group followed expectantly, whereas no stillbirths were seen in the early induction group. Conclusions: Induction of labor for prolonged pregnancy in low-risk patients soon after the 41 weeks, reduces the proportion of small-for-gestational age babies, but increases the mean hospital stay as well as the need for delivery by caesarean section, including that for failed induction.

Keywords::

• cesarean section
• labor induction
• prolongued pregnancy
• post-term pregnancy
• small-for-gestational age

Acknowledgements

The study was supported by a grant from Aragon Institute of Health Sciences, “Reproductive Medicine Research Group” (B-87).

Declaration of interest: The authors declare not having conflict of interests regarding this study.