The authors calculated there would be a 3.7 percent decrease in stillbirths if all women went to sleep on their sides in the final trimester. Picture: Pixabay

London - Women who sleep on their back in the last three months of pregnancy are twice as likely to suffer a stillbirth, researchers have warned.

A study of more than 1 000 pregnant women in England found a 2.3-fold increase in the risk of late stillbirth among those who slept on their backs.

The authors, from St Mary’s Hospital in Manchester, calculated there would be a 3.7 percent decrease in stillbirths if all women went to sleep on their sides in the final trimester.

This would save the lives of roughly 120 babies a year.

The Tommy’s stillbirth charity, which funded the research, advised women should sleep on their sides but not be concerned if they wake up on their back as the position at falling asleep is usually held longest during the night.

Should they wake in the middle of the night they should roll on to their sides before going back to sleep, the charity said.

The researchers, whose work is published in the British Journal of Obstetrics and Gynaecology, think these figures could be brought down if basic advice is followed.

Study leader Professor Alexander Heazell, clinical director at the Tommy’s Stillbirth Research Centre at St Mary’s Hospital, said: "Around 11 babies are stillborn every day in the UK. Parents want to know why their baby has died, whether it might happen again if they try for another baby and what they can do to avoid further stillbirth."

Many pregnant women find lying on their back uncomfortable – but roughly 10 percent still sleep on their backs at night.

Scientists are unsure exactly why this is dangerous, but believe it may block blood flow to the baby or affect the mother’s breathing.

In most cases, the cause of a stillbirth is unknown, but many are caused by problems with the placenta – the lifeline providing the baby with oxygen and nourishment as it grows in the womb. 

Louise Silverton, director for midwifery at the Royal College of Midwives, said: "Stillbirth is a terrible tragedy for mothers and their families and we must do all we can to bring stillbirth rates down.

"This addition to current knowledge is very welcome. The Tommy’s campaign and the research findings are a great example of how through making small changes we can begin to bring down stillbirth rates.

"It is a simple change that can make a difference and it will be important to ensure that this is communicated effectively to women."