University of Michigan-led study shows maternal sleep position may influence pregnancy outcomes

Pregnant women in Ghana who slept on their back (supine sleep) were at an increased risk of stillbirth compared to women who did not sleep on their back, according to new research led by a University of Michigan researcher.

In the study, published this month in the International Journal of Gynecology and Obstetrics, researchers found that supine sleep increased the risk of low birth weight by a factor of 5 and that it was the low birth weight that explained the high risk for stillbirth in these women.

The study's senior author, Louise O'Brien, Ph.D., M.S., associate professor in U-M's Sleep Disorders Center, says that although this study was conducted in a maternity hospital in Ghana -- a country that has high perinatal mortality -- a recent case-control study from New Zealand also found a link between maternal supine sleep and stillbirth.

Stillbirth is a traumatic event that occurs in about 2-5 babies out of every 1,000 babies born in high-income countries. In low income countries, such as those in Africa, about 20-50 babies out of every 1,000 babies are stillborn.

"But if maternal sleep position does play a role in stillbirth, encouraging pregnant women everywhere not to sleep on their back is a simple approach that may improve pregnancy outcomes," says O'Brien.

Sub-Saharan Africa has the highest rate of stillbirth in the world and little progress has been made in reducing those deaths.

"In Ghana, inexpensive interventions are urgently needed to improve pregnancy outcomes. This is a behavior that can be modified: encouraging women to avoid sleeping on their back would be a low-cost method to reduce stillbirths in Ghana and other low-income countries," says O'Brien.

Jocelynn Owusu, M.P.H., of the Department of Health Behavior and Education in the U-M School of Public Health, the study's first author, interviewed women soon after delivery at Korle Bu Teaching Hospital in Accra Ghana.

O'Brien says that the possibility that supine sleep has a part in low birth weight and subsequently stillbirth is plausible because of uterine compression on the inferior vena cava, resulting in reduced venous filling and cardiac output.

"The data in this study suggests that more than one-quarter of stillbirths might be avoided by altering maternal sleep position," O'Brien says. "This supports the need to develop simple intervention trials."

Source: University of Michigan Health System