STUDY QUESTION: Does 15 min of immobilization after IUI improve pregnancy rates?
SUMMARY ANSWER: Immobilization for 15 min after IUI does not improve pregnancy rates.
WHAT IS KNOWN ALREADY: Prior RCTs report a beneficial effect of supine immobilization for 15 min following IUI compared to immediate mobilization, however, these studies can be criticized. Given the importance for the logistics in daily practice and the lack of biological plausibility we planned a replication study prior to potential implementation of this procedure.
STUDY DESIGN, SIZE, DURATION: A single centre RCT, based in an academic setting in the Netherlands, was performed. Participants were randomly assigned for 15 min of supine immobilization following IUI for a maximum of six cycles compared to the standard procedure of immediate mobilization following IUI. Participants and caregivers were not blinded to group assignment. An independent researcher used computer-generated tables to allocate treatments. Stratification occurred to the indication of IUI (unexplained or mild male subfertility). Revelation of allocation took place just before the insemination by the caregiver. The primary outcome was ongoing pregnancy rate per couple.
PARTICIPANTS/MATERIALS, SETTING, METHODS: A total of 498 couples diagnosed with unexplained or mild male subfertility and an indication for treatment with IUI were approached and randomized in the study, of which 244 participants were assigned to 15 min of supine immobilization and 254 participants to immediate mobilization.
MAIN RESULTS AND THE ROLE OF CHANCE: Participant characteristics were comparable between the groups, and 236 participants were analysed in the immobilization group, versus 245 in the mobilization group. The ongoing pregnancy rate per couple was not found to be superior in the immobilization group (one-sided P-value = 0.97) with 76/236 ongoing pregnancies (32.2%) being accomplished in the immobilization and 98/245 ongoing pregnancies (40.0%) in the immediate mobilization group (relative risk 0.81; 95% CI [0.63, 1.02], risk difference: -7.8%, 95% CI [-16.4%, 0.8%]). No difference was found in miscarriage rate, multiple gestation rate, live birth rate and time to pregnancy between the groups.
LIMITATIONS, REASONS FOR CAUTION: Owing to discontinuation of the planned treatment not all participants reached six IUI cycles or an ongoing pregnancy. However, this is as expected in IUI treatment and mirrors clinical practice. These participants were equally distributed across the two groups. Women with tubal pathology and endocrine disorders were excluded for this trial, and this might narrow generalizability.
WIDER IMPLICATIONS OF THE FINDINGS: This study shows no positive effect of 15 min of immobilization following IUI on pregnancy rates. Based on available evidence today, including our study, a possible beneficial effect of supine immobilization after IUI is at least doubtful and straightforward implementation does not seem to be justified.
STUDY FUNDING/COMPETING INTEREST(S): No funding was received. All authors have nothing to disclose.
TRIAL REGISTRATION NUMBER: Dutch Trial Register NTR 2418.
TRIAL REGISTRATION DATE: 20 July 2010.
DATE OF FIRST PATIENT's ENROLMENT: 11 August 2010.