Comparison of induction of labour and expectant management in postterm pregnancy: a matched cohort study

Randomized clinical trials have shown that induction of labour does not result in higher caesarean delivery rates in women who are postterm. Despite this evidence, the policy of inducing women who are postterm is not generally applied in the Netherlands. This provides us with the opportunity to assess whether the findings from randomized studies can also be observed in nonrandomized studies and to validate these findings in the Dutch obstetric population. We performed a retrospective matched cohort study (1:1 ratios for both age and parity) in women with uncomplicated pregnancies of 42 weeks' duration and compared induction of labour with a policy of serial antenatal monitoring. Analyses were made by the intention to treat principle. We studied 674 women. Among the 337 women in the expectant management group, 42 (12.5%) underwent caesarean delivery, compared to 46 (13.6%) of the 337 women in the induction group (relative risk [RR], 0.9; 95% confidence interval [CI], 0.6-1.4). However, the incidence of shoulder dystocia (RR, 4.3; 95% CI, 1.3-15) and meconium-stained amniotic fluid (RR, 1.8; 95% CI, 1.4-2.3) were higher in the expectant management group. Induction of labour does not result in an increased risk of caesarean delivery in women who are postterm. Because epidemiologic studies suggest an increased risk of perinatal death and birth injury beyond 42 weeks' gestation, induction of labour should be offered to all women who are postterm.