Sleeping on right side may increase stillbirth risk

Experts found a link between sleeping position and the chance of late stillbirth (28 weeks or over) in a study of more than 450 women. The overall risk of late stillbirth was small – just three per 1,000 births – but researchers said the findings needed “urgent confirmation” in other studies.

Some 155 women who had a late stillbirth were questioned about their lifestyles, and compared with 310 women who went on to have healthy pregnancies.

The women were questioned in the first few weeks after stillbirth and asked about things such as the positions they fell asleep and woke up in, whether they were sleepy during the day and whether they snored. They were also asked how often they got up to go to the toilet during the night, and how often they did all of these things in the last month, week and night before their baby died.

The research found that women who slept on their back or on their right side on the previous night before stillbirth were twice as likely to experience stillbirth compared with women who slept on their left side.

The absolute risk of late stillbirth for women who went to sleep on their left was 1.96 per 1,000 births but rose to 3.93 per 1,000 for women who slept in any other position. The risk seemed to be slightly higher for women who went to sleep on their back.

Previous studies have found that a woman’s position in late pregnancy, either when resting or giving birth, can have an impact on cardiac output and delivery of oxygen to the foetus.

The womb seems to exert greater pressure on blood vessels when the mother lies on her back or her right, thereby decreasing blood flow. Writing online in the British Medical Journal, the experts, from the University of Auckland, called for further studies to test the findings.