Sleep position in pregnancy linked to stillbirth risk

A woman who sleeps on her right side or back during the late stages of pregnancy may have double the risk of stillbirth compared to women who sleep on their left side, according to a new study.

However, the researchers from the University of Auckland, New Zealand, stressed that the overall risk of having a stillborn child was still small.

The study involved 155 women who had given birth to a still born baby when they were at least 28 weeks pregnant, and 310 women who had healthy pregnancies.

The research was originally carried out to look at how sleep might affect the risk of having a stillborn baby, as some sleep disorders may reduce the amount of oxygen which gets to the baby.

All the women in the study were questioned about their sleep position and sleep patterns in the last weeks and days before they thought their baby had died.

The researchers found the absolute risk of a late stillbirth for women who went to sleep on their left was 1.96 per 1,000 women, but 3.93 per 1,000 for those who slept in any other position, such as their back or right side.

Although the absolute risk for women is still low, they said the findings could be important at a population level, but need to be confirmed by other studies.

The study also found also that women who get up to go to the toilet once or less on the last night of pregnancy, and those who regularly sleep during the day in the last month of pregnancy, are more likely to have a stillborn baby.

The researchers suggested that a restricted blood flow to the baby when the mother lies on her back or right side for long periods may help to explain the link.

They said that more studies were needed before any recommendations on sleeping positions during pregnancy could be made, but concluded: “If our findings are confirmed, promoting optimal sleep position in late pregnancy may have the potential to reduce the incidence of late stillbirth.”

In an editorial in the British Medical Journal, where the study is published, Dr Lucy Chappell from King's College London said that "any simple intervention that reduces the risk of stillbirth would be extremely welcome," given that the UK has one of the highest rates of stillbirth in the developed world.

However, Dr Chappell also cautioned that the study findings were not conclusive and "a forceful campaign urging pregnant women to sleep on their left side is not yet warranted."

This article was published on Wed 15 June 2011