Pregnant women who sleep on their backs may increase the risk of miscarriage, a research in Australia has found.  The study, known as the Sydney Stillbirth Study, looked at the pregnancies of 295 women from eight hospitals around Australia. The five-year study found that women who sleep on their backs are six times more likely to have a stillborn baby. Lead researcher, Dr Adrienne Gordon, from Sydney’s Royal Prince Alfred Hospital, said previous research had suggested prolonged periods in this position ristricted blood flow tothe baby.

It’s thought that sleeping on the right side or on the back reduces blood flow through a major vein from the legs to the heart, which affects the supply to the womb. The researchers added it was important that women who are currently pregnant “don’t become alarmed if they sometimes sleep on their back.” Experts have pointed out previously that three-quarters of pregnant women sleep mostly on the left side – higher than the rate in women who are not pregnant.

A stillborn baby is a baby born dead after 24 weeks of pregnancy. If the baby dies before 24 weeks, it is known as a late miscarriage. There are around 4,000 stillbirths every year in the United Kingdom, UK, and 11 babies are stillborn every day in the UK, making it 10 times more common than cot death. In almost half of stillbirths, the direct cause of the baby’s death cannot be established.  Ten per cent of stillborn babies have some kind of abnormality and other possible causes include problems with the mother’s health or problems with the placenta, which links the baby’s blood supply to the mother’s.

Stillbirth Foundation Australia, which funded the research, said the study was unique as it looked exclusively at women who were more than 32 weeks pregnant. “It’s in this later stage of pregnancy that the largest proportion of stillbirths occur,” said Emma McLeod, director of the Stillbirth Foundation Australia. She added that, “For around 40 per cent of stillbirths after 32 weeks, they are otherwise perfectly healthy babies and there is no medical explanation as to why they died.”  In addition to sleep position, significant risk factors for stillbirth include how much the baby moved and whether it was the size it should be for its age.

“We found an association with decreased movements and stillborn babies,” Gordon noted.  On the other hand, in women with healthy pregnancies who had a live birth, the frequency and strength of the babies’ movements actually increased later in the pregnancy. Gordon added: “This may debunk the myth that it’s normal for a baby’s movement to slow down at the end of pregnancy. We didn’t find that at all.”