Activity restriction for women with arrested preterm labor: a randomized controlled trial

Objective: This study aimed to test the hypothesis that in women with singleton pregnancy and arrested preterm labor, activity restriction would reduce the rate of preterm birth at <37 weeks of gestation. Study design: This was a parallel-group nonblinded randomized trial conducted at a single center in Italy. Eligible patients were those with a diagnosis of arrested preterm labor, defined as not delivering after 48 hours of hospitalization for threatened preterm labor, with transvaginal ultrasound cervical length ≤25 mm, no other symptoms of possible uterine contractions, and cervical dilatation <3 cm at pelvic examination. Inclusion criteria were singleton pregnancies between 24 0/7 and 33 6/7 weeks of gestation. Participants were randomized in a 1:1 ratio to either activity restriction at the time of discharge or no activity restriction. Women in the intervention group were recommended activity restriction, defined as the following: pelvic rest, prohibition of sexual activity, and reduction of work and/or nonwork activity. The primary endpoint was preterm birth at <37 weeks of gestation. Results: A total of 120 participants were included in the trial; 60 patients were enrolled in the activity restriction group and 60 in the control group. Preterm birth at <37 weeks of gestation occurred in 15 of 60 women (25.0%) in the activity restriction group and 23 of 60 women (38.3%) in the control group (relative risk, 0.65; 95% confidence interval, 0.38-1.12). There was no significant between-group difference in the incidence of preterm birth at <32 weeks and in neonatal outcomes, but the trial was not powered for these outcomes. Conclusion: In singleton gestations with arrested preterm labor, activity restriction, including pelvic rest, prohibition of sexual activity, and reduction of work and/or nonwork activity, does not result in a lower rate of preterm birth at <37 weeks. Given the evidence on the lack of benefits, use of activity restriction in this population should be discouraged.