Maternal sleep practices and stillbirth risk

Midwives magazine: Issue 6 :: 2011

Paper | Association between maternal sleep practices and risk of late stillbirth: a case-control study.
Author | Stacey T, Thompson J, Mitchell E, Ekeroma A, Zuccollo J, Mc Cowan L.
Publication | British Medical Journal 2011; 342: d3403.

The objective of this study, undertaken in Auckland, New Zealand, was to determine whether various sleep patterns, such as snoring and sleep position, are associated with the risk of late stillbirth. A third of a person’s life is spent asleep, say the authors, but there has been little research on the potential impact of sleep practices on the developing fetus, although it has been shown that cardiac output and fetal oxygen saturation are influenced by maternal body position in pregnancy. There has been little change in the stillbirth rate over the past two decades.

Participants were 155 women with a singleton late stillbirth (at more than 28 weeks’ gestation) and 310 controls who gave birth between July 2006 and June 2009. There were no differences in ethnicity, age or parity. Women were excluded if their baby died from a congenital abnormality or was from a multiple pregnancy. The prevalence of late stillbirth in the study was 3.09 per 1000 births. Data were obtained through an interviewer-administered questionnaire in the first few weeks after stillbirth.

It was not possible to ascertain changes in sleep position during the night, so position on going to sleep and position on waking were recorded. Sleep position was classified as left side, right side, back and ‘other’. Sleeping on the back appeared to carry the greatest risk. No relation was found between snoring or daytime sleepiness and risk of late stillbirth. Women who slept on their left side on the last night of pregnancy had a reduced risk of late stillbirth compared with those who slept in any other position, such as on their back or on the right side. The absolute risk of late stillbirth for women who went to sleep on their left side was 1.96 per 1000; for those who did not go to sleep on their left, it was 3.93 per 1000.

There was an association between getting up to go to the toilet during the night – women who got up once or more on the last night of pregnancy were more likely to experience late stillbirth compared with women who got up less frequently (adjusted odds ratio 2.28 [1.40 to 3.71]). Women who slept regularly during the day in the previous month were also more likely to experience a late stillbirth than those who did not (adjusted odds ratio 2.04 [1.26 to 3.27]). Women with late stillbirth were more likely to be obese, socio-economically deprived, to smoke and be of high parity compared with controls.

The authors assert that their study has identified a potentially modifiable risk factor for late stillbirth. If their findings are confirmed, promoting optimal sleep position in late pregnancy may have the potential to reduce the incidence of late stillbirth. Further research is needed. 


Overview

Women who did not go to sleep on their left side on the last night before fetal death had a doubled risk of late stillbirth compared with those who went to sleep on their left side.

Women who went to the toilet twice or more during the night were more likely to experience a late stillbirth.