Effect of Coital Activity on Onset of Labor in Women Scheduled for Labor Induction: A Randomized Controlled Trial

Abstract

Coital activity at term reportedly is associated with shorter gestation and less need to induce labor because of prolonged pregnancy, but such findings have not been consistently affirmed. In this randomized study, 108 women scheduled to have nonurgent induction of labor at term (37 weeks' gestation or later) were randomly assigned to be advised to have vaginal intercourse with the goal of hastening the onset of labor. They were told that intercourse late in pregnancy was safe and could promote the onset of labor. The 102 women in a control group were neither encouraged nor discouraged to have coitus. Labor was induced by amniotomy if the cervix was favorable and by vaginal dinoprostone if it was unfavorable. All participants kept a coital and orgasm diary and received standard obstetrical care. The rate of reported coital activity was 60% in women advised to have sex and 40% in control women; the relative risk was 1.5, with a 95% confidence interval of 1.1 to 2.0. Nevertheless, rates of spontaneous labor did not differ significantly; they were 56% in the study group and 52% in control women. More than 80% of women who reported one or more episodes of vaginal sex after randomization also reported having at least one orgasm. The 2 groups did not differ significantly with regard to either the timing of admission for birth or spontaneous labor, or presentation at admission for birth. There also were no group differences in rates of cesarean delivery, maternal fever, or neonatal outcomes. These findings do not validate the practice of advising women scheduled for induction of labor at term to have vaginal intercourse in order to hasten the onset of labor.