INTRODUCTION: Sleep disturbances are increasing in prevalence in North America. Because many reproductive hormones critical for pregnancy maintenance have been found to exhibit a circadian pattern under normal sleep conditions, disrupted sleep can deleteriously affect these patterns. Several studies of women undergoing in vitro fertilization, as well as animal models, have suggested that sleep disturbances during the periconception period may result in implantation failure or spontaneous abortion (SAB). However, few prospective studies have examined the association between sleep disturbances and SAB. We evaluated the association between preconception sleep patterns and SAB among couples attempting to conceive spontaneously.
METHODS: Pregnancy Study Online is a web-based preconception cohort study of North American pregnancy planners. During the preconception period, female participants completed a baseline questionnaire providing data on demographic and lifestyle factors, average duration of sleep per night, and frequency of trouble sleeping at night (via the Major Depression Inventory). We followed participants via bi-monthly questionnaires for up to 12 months or until reported conception. Data on SAB, first positive pregnancy test date, due date, and gestational weeks at loss were ascertained from follow-up questionnaires in both early (<12 weeks’ gestation) and late (~32 weeks’ gestation) pregnancy. We used Cox proportional hazards regression to estimate hazard ratios (HR) and 95% confidence intervals (CI), using gestational weeks as the time scale. We adjusted for age, body mass index, and lifestyle and demographic factors.
RESULTS: Of the 5,615 participants who conceived, 1,044 (19%) reported an SAB. The median gestational week at loss was 7 weeks (interquartile range: 5-9 weeks). Relative to 8 hours of sleep before conception, HRs for <6, 6, 7, and ≥9 hours of sleep were 0.87 (95% CI: 0.63-1.21), 1.16 (95% CI: 0.97-1.40), 1.08 (95% CI: 0.93-1.26), and 0.97 (95% CI: 0.73-1.29). Compared with women who had no trouble sleeping before conception, HRs for women who had trouble sleeping “sometimes” or “less than half of the time” and “more than half of the time” or “all of the time” were 0.99 (95% CI: 0.86-1.13) and 1.19 (95% CI: 1.00-1.42).
CONCLUSION: Sleep duration was not appreciably associated with increased risk of SAB. However, we observed a small increased risk of SAB among women who reported a high frequency of trouble sleeping at night during the preconception period. Limitations include use of a single baseline measure of sleep and the potential for residual confounding.
