A lot of women ask this question because they’ve been told to never sleep on their backs, particularly in the third trimester. Much advice on the Internet and in books about pregnancy recommends against sleeping on your back. There is no good scientific evidence that sleeping on the back increases the risk of stillbirth, and even in the third trimester. There have been studies that show that babies have some fetal heart rate changes in different sleep patterns while the mother is sleeping on her back, but these changes have not been definitively associated with an increased risk of stillbirth.

What’s more, a woman has little control over her sleeping position. Women in the third trimester are unlikely to sleep on their backs in the first place due to their belly size, so they will naturally tend to sleep on one side or the other anyway. If they should sleep on their backs, there is little to do about it since women have no control over how they turn and flip about during sleep. Since there has been no definitive connection between back sleeping and stillbirth, then women should not lose too much sleep (pun intended) worrying about how they sleep.