Ambulation for latency during expectant management of preterm prelabor rupture of membranes: a randomized controlled trial (AMBLE)

Abstract

BackgroundIndividuals hospitalized with preterm prelabor rupture of the membranes (PPROM) are often advised to limit their activity or adhere to bedrest. Some evidence suggests that greater activity is associated with longer latency and improved outcomes, but no high-quality evidence from a randomized-controlled trial exists. ObjectiveTo evaluate whether encouragement to ambulate at least 2,000 steps daily impacts latency among individuals with PPROM compared with usual care. Study DesignMultisite unblinded, two-arm randomized trial of individuals at 23 0/7 to 35 0/7 weeks gestation undergoing inpatient expectant management of PPROM with planned delivery at least 7 days away. Each participant wore a Fitbit InspireTM that tracked steps. The intervention arm was encouraged (verbal and Fitbit-based reminders) to reach a goal of 2,000 steps per day. The usual care arm was allowed ad lib activity with no step goal or reminders. The primary outcome was latency (days) from randomization to delivery. Secondary analyses included composite neonatal and maternal clinical outcomes and maternal mental health survey results. Statistical analyses were intent-to-treat under a Bayesian framework using neutral priors (a priori assumed 50:50 likelihood of longer latency in either arm). 100 participants were required to have 80% power to demonstrate a 4-day difference in latency with 75% certainty (Bayesian probability). ResultsAmong 163 eligible individuals, 100 (61%) were randomized, and after loss to follow-up, 95 were analyzed. Gestational age at randomization was 29 3/7 weeks (interquartile range [IQR] 26 2/7, 31 5/7) in the intervention arm and 27 4/7 weeks (IQR 25 4/7, 29 6/7) in the usual care arm. Median step counts were 1,690/day in the intervention arm (IQR 1,031-2,641) and 1,338/day in the usual care arm (IQR 784-1,913). Median days of latency were 9 days in the intervention arm (IQR 4-17) and 6 days in the usual care arm (IQR 2-14). The primary analysis indicated a 65% posterior probability that the intervention increased latency versus usual care (posterior relative risk [RR] 1.09; 95% credible interval [CrI], 0.70-1.71). The RR for composite neonatal adverse outcome was 0.55 (95% CrI 0.32-0.82) with 99% posterior probability of intervention benefit and for composite maternal adverse outcome was 0.94 (95% CrI 0.72-1.20), with 70% posterior probability of intervention benefit. There was a 94% posterior probability of the intervention arm having a greater decrease in maternal stress score from baseline to before delivery compared with the usual care arm (mean arm difference 3.24 points [95% CrI -7.23-0.79]). Adjustment for gestational age at randomization had minimal impact on secondary outcome results. ConclusionsIndividuals with PPROM randomized to encouragement to ambulate had a longer latency to delivery and improved neonatal and mental health outcomes with similar maternal clinical outcomes compared to usual care.