Have you heard that sleeping on your side during the third trimester of pregnancy is important?

Sleeping on your back rests all of the weight of the baby on your back and on veins that carry blood to the heart – it may actually lead to reduced blood flow to the growing baby. That’s been linked to an increased risk of stillbirth late in pregnancy and now to low birth weight as well.

The researchers analysed data from Australian, New Zealand and British women who were in their third trimester of pregnancy. They looked at what position the women fell asleep in each night and then followed them through to birth to see when the baby came and its weight.

More than 1700 women from a variety of ethnic backgrounds were included in the study and about three per cent of them said they regularly went to sleep lying on their back.

The study found that going to sleep on one’s back was linked to a three-fold increase in having a baby that was small for its gestational age, independent of other variables that are known to reduce a baby’s birth weight (such as maternal blood pressure and diabetes).

Implications

This adds to existing evidence suggesting women in late-stage pregnancy should avoid sleeping on their back.

A baby born small for gestational age may have poorer health outcomes, and the authors say public health campaigns should continue to encourage pregnant women to sleep on their sides.

Last Reviewed: 26/10/2020

Your Doctor. Dr Michael Jones, Medical Editor.



References

For reference: Anderson, et al (2019). Association of Supine Going-to-Sleep Position in Late Pregnancy With Reduced Birth Weight. Science of Learning doi: 10.1001/jamanetworkopen.2019.12614.

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