Senior author Louise O'Brien, an associate professor in University of Michigan's Sleep Disorders Center, and colleagues and said although the study was conducted in a maternity hospital in Ghana, a recent case-control study from New Zealand also found a link between maternal supine sleep -- sleeping on their backs -- and stillbirth.
Stillbirth occurs in about two to five babies out of every 1,000 babies born in high-income countries, but undeveloped countries about 20-50 babies out of every 1,000 babies are stillborn, O'Brien said.
"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," O'Brien said in a statement.
"In Ghana, inexpensive interventions are urgently needed to improve pregnancy outcomes. Encouraging women to avoid sleeping on their back would be a low-cost method to reduce stillbirths in Ghana and other low-income countries."
O'Brien said the possibility that supine sleep has a part in low-birth weight and subsequently in stillbirths was plausible because of uterine compression 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 said. "This supports the need to develop simple intervention trials."