Results from a randomized clinical trial evaluating a variety of maternal and neonatal outcomes showed that for primigravid women ages 35 and older with an uncomplicated pregnancy, labor induction near term neither afforded benefits nor increased risks compared with expectant management.1
Conducted in the United Kingdom, the multicenter study enrolled 619 women who had a singleton live fetus in a cephalic presentation with no known congenital abnormality and no contraindications to labor, vaginal delivery, or expectant management. Women were randomized to labor induction or expectant management after stratification by maternal age (35 to 37 years, 38 to 39 years, ≥40 years).
Cesarean delivery was analyzed as the primary outcome, and the rate did not differ significantly comparing the labor induction and expectant management groups (32% vs 33%; relative risk, 0.99; 95% confidence interval, 0.87 to 1.14].
In addition, there were no statistically significant differences between the labor induction and expectant management groups in any secondary endpoints.
“Although our study was not designed or powered to assess the effects of labor induction on stillbirth, based on the outcomes analyzed, labor induction at 39 weeks remains a reasonable choice for older women who are worried about late stillbirth,” said James Thornton, MD, professor of obstetrics and gynaecology, University of Nottingham, UK.
“However, labor induction did not prove to reduce any adverse outcomes. Furthermore, we cannot be certain there are no long-term effects on the baby because we do not yet have data from follow-up after discharge. Therefore, women who so desire should feel free to await spontaneous labor.”
In developing the study, the investigators noted that there is a small but definite increased risk of antepartum stillbirth at term among women ages 35 years and older relative to their younger counterparts. However, labor induction is associated with increased rate of cesarean delivery and other risks.
In addition, the proportion of women who are becoming pregnant at age 35 and older has been steadily increasing in the Western world, but there is no evidence basis for counseling them about the choice between labor induction and expectant management. Previous research comparing these 2 strategies in women of advanced maternal age either focused on a population with complicated pregnancy or were small studies dating back to the 1970s.
“Women have very polarized views about induction. Some are keen to be induced near their due date because they are tired of the pregnancy and/or worried about the risk of stillbirth. Others, however, feel that nature knows best and induction is meddlesome, usually unnecessary, and often leads to a cascade of interventions that may do more harm than good. Both groups have valid motivations, and we wanted to provide some hard data on the issues,” Dr Thornton told Contemporary OB/GYN.
A total of 6455 women were evaluated for participation in the trial, of whom 3923 who were eligible declined to participate. Almost half of the latter group expressed a preference for labor induction or expectant management and their preference was overwhelmingly for expectant management (88%).
The study protocol included a prespecified subgroup analysis of cesarean delivery rates according to maternal age, and its results also showed no statistically significant differences between labor induction and expectant management among women of any age subgroup.
Secondary maternal outcomes looked at method of delivery other than cesarean section, onset of labor, indication for induction of labor, method of labor induction, indication for cesarean section, intrapartum complications, and postpartum complications. In addition, the mothers’ expectations and experience of childbirth were evaluated with completion of the Childbirth Experience Questionnaire 1 month after delivery.
Secondary neonatal outcomes were live birth or still birth, birth weight, admission to a neonatal intensive care unit, birth trauma, direct trauma, and hypoxia.
Discussing the study’s limitations, the investigators noted the findings regarding childbirth experience may not apply to women who prefer a particular strategy. In addition, the results for the other maternal outcomes and the neonatal outcomes may not be generalizable to older multiparous women or nulliparous women aged 35 or older with complicated pregnancies.
1. Walker KF, Bugg GJ, Macpherson, et al., for the 35/39 Trial Group. Randomized trial of labor induction in women 35 years of age or older. N Engl J Med. 2016;374(9):813–822.