ObjectiveTo report maternal sleep practices in women who experienced a stillbirth compared with controls with ongoing live pregnancies at similar gestation.DesignProspective case‐control study.SettingForty‐one maternity units in the United Kingdom.PopulationWomen who had a stillbirth after ≥ 28 weeks’ gestation (n = 291) and women with an ongoing pregnancy at the time of interview (n = 733).MethodsData were collected using an interviewer‐administered questionnaire that included questions on maternal sleep practices before pregnancy, in the four weeks prior to, and on the night before the interview/stillbirth.Main outcome measuresMaternal sleep practices during pregnancy.ResultsIn 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 with the left side. In addition, women who had a stillbirth were more likely to report sleep duration less than 5.5 hours on the night before stillbirth (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 gestational age. The population‐attributable risk for supine going‐to‐sleep position was 3.7% (95% CI 0.5–9.2).ConclusionsThis 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.Tweetable abstractSupine going‐to‐sleep position is associated with 2.3× increased risk of stillbirth after 28 weeks’ gestation.Plain Language SummaryStillbirth, the death of a baby before birth, is a tragedy for mothers and families. One approach to reduce stillbirths is to identify factors that are associated with stillbirth. There are few risk factors for stillbirth that can be easily changed, but this study is looking at identifying how mothers may be able to reduce their risk.In this study, we interviewed 291 women who had a stillbirth and 733 women who had a live‐born baby from 41 maternity units throughout the UK. The mothers who had a stillbirth were interviewed as soon as practical after their baby died. Mothers who had a live birth were interviewed during their pregnancies at the same times in pregnancy as when the stillbirths occurred. We did not interview mothers who had twins or who had a baby with a major abnormality.Mothers who went to sleep on their back had at least twice the risk of stillbirth compared with mothers who went to sleep on their left‐hand side. This study suggests that 3.7% of stillbirths after 28 weeks of pregnancy were linked with going to sleep lying on the back. This study also shows that the link between going‐to‐sleep position and late stillbirth was not affected by the duration of pregnancy after 28 weeks, th...

Objective To explore the separate effects of being ‘at risk’ of gestational diabetes mellitus (GDM) and screening for GDM, and of raised fasting plasma glucose (FPG) and clinical diagnosis of GDM, on the risk of late stillbirth. Design Prospective case–control study. Setting Forty‐one maternity units in the UK. Population Women who had a stillbirth ≥28 weeks of gestation (n = 291) and women with an ongoing pregnancy at the time of interview (n = 733). Methods Causal mediation analysis explored the joint effects of (i) ‘at risk’ of GDM and screening for GDM and (ii) raised FPG (≥5.6 mmol/l) and clinical diagnosis of GDM on the risks of late stillbirth. Adjusted odds ratios (aOR) were estimated by logistic regression adjusted for confounders identified by directed acyclic graphs. Main outcome measures Screening for GDM and FPG levels Results Women ‘at risk’ of GDM, but not screened, experienced 44% greater risk of late stillbirth than those not ‘at risk’ (aOR 1.44, 95% CI 1.01–2.06). Women ‘at risk’ of GDM who were screened experienced no such increase (aOR 0.98, 95% CI 0.70–1.36). Women with raised FPG not diagnosed with GDM experienced four‐fold greater risk of late stillbirth than women with normal FPG (aOR 4.22, 95% CI 1.04–17.02). Women with raised FPG who were diagnosed with GDM experienced no such increase (aOR 1.10, 95% CI 0.31–3.91). Conclusions Optimal screening and diagnosis of GDM mitigate the higher risks of late stillbirth in women ‘at risk’ of GDM and/or with raised FPG. Failure to diagnose GDM leaves women with raised FPG exposed to avoidable risk of late stillbirth. Tweetable abstract Risk of #stillbirth in gestational diabetes is mitigated by effective screening and diagnosis.