Association between maternal sleep practices and late stillbirth – findings from a stillbirth case‐control study

Objective: To report maternal sleep practices in women who experienced a stillbirth compared to controls with ongoing live pregnancies at similar gestation. Design: Prospective case-control study. Setting: 41 maternity units in the United Kingdom. Population: Women who had a stillbirth ≥28 weeks’ gestation (n=291) and women with an ongoing pregnancy at the time of interview (n=733). Methods: Data were collected using an interviewer-administered questionnaire which included questions on maternal sleep practices before pregnancy, in the four weeks prior to and on the night before the interview/stillbirth. Main outcome measure: Maternal sleep practices during pregnancy. Results: In multivariable analysis, supine going-to-sleep position the night before stillbirth had a 2.3-fold increased risk of late stillbirth (adjusted Odds Ratio (aOR) 2.31, 95%CI 1.04-5.11) compared to the left side. In addition, women who had a stillbirth were more likely to report sleep duration less than 5.5 hours on the last night (aOR 1.83, 95%CI 1.24-2.68), getting up to the toilet once or less (aOR 2.81, 95%CI 1.85-4.26) and a daytime nap every day (aOR 2.22, 95%CI 1.26-3.94). No interaction was detected between supine going-to-sleep position and a small for gestational age infant, maternal body mass index or gestation. The population attributable risk for supine going-to sleep position was 3.7% (95% CI 0.5-9.2). Conclusions: This study confirms that supine going-to-sleep position is associated with late stillbirth. Further work is required to determine whether intervention(s) can decrease the frequency of supine going to sleep position and the incidence of late stillbirth.