(PhysOrg.com) -- In a new study published in the British Medical Journal, Tomasina Stacey from the University of Aucklands Department of Obstetrics and Gynecology revealed that women who do not sleep on their left side during the last nights of pregnancy increase their risk of stillbirth by twice as much.
While sleeping on the back or right side does create an increased risk, the overall risk is still small at 3.93 stillbirths out of 1,000. Sleeping on your back or right side can restrict the blood flow to the baby and the researchers believe that this restricted blood flow is to blame for the increased risk.
The team of researchers looked at data collected from the Auckland Stillbirth Study that included 155 women that had stillbirths at 28 weeks or more as well as 310 controls in the same gestational period who delivered healthy babies.
Sleeping position was not the only factor they found that could possibly contribute to the stillbirth rates. Lower socioeconomic status, smokers and heavier weight were also contributing factors in the mothers who delivered stillborn infants.
Other factors that can increase the risk factor of stillborn infants are sleeping during the day during the last month, getting more than eight hours of sleep at night and using the bathroom infrequently during the last month of pregnancy.
The researchers point out that this is the first study that looks at the connection between a mothers sleep position and stillborn risk, and they believe that further study is needed. Similar to the promotion and awareness to changing an infants sleeping pattern and its effect on the rates of SIDS deaths, the researchers hope that if more studies confirm these findings, the promotion of a change in mothers sleep patterns could reduce the risk of stillborn births.
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More information: Association between maternal sleep practices and risk of late stillbirth: a case-control study, BMJ 2011; 342:d3403 doi:10.1136/bmj.d3403 (Published 14 June 2011)
The prevalence of late stillbirth in this study was 3.09/1000 births. No relation was found between snoring or daytime sleepiness and risk of late stillbirth. However, women who slept on their back or on their right side on the previous night (before stillbirth or interview) were more likely to experience a late stillbirth compared with women who slept on their left side (adjusted odds ratio for back sleeping 2.54 (95% CI 1.04 to 6.18), and for right side sleeping 1.74 (0.98 to 3.01)). The absolute risk of late stillbirth for women who went to sleep on their left was 1.96/1000 and was 3.93/1000 for women who did not go to sleep on their left. Women who got up to go to the toilet once or less on the last night were more likely to experience a late stillbirth compared with women who got up more frequently (adjusted odds ratio 2.28 (1.40 to 3.71)). Women who regularly slept during the day in the previous month were also more likely to experience a late stillbirth than those who did not (2.04 (1.26 to 3.27)).