Understanding the evidence about side sleeping to reduce the risk of stillbirth will assist maternity clinicians to have more meaningful conversations with women before they reach 28 weeks gestation.
Going to sleep in the supine position (on the back) in late pregnancy is a recently identified and modifiable risk factor for late stillbirth. New research shows that women can halve their risk of stillbirth by going to sleep on their side from 28 weeks pregnancy compared with sleeping in the supine position.
Accumulating evidence has shown an association between maternal supine going-to-sleep position and stillbirth > 28 weeks’ gestation. In the past five years there have been several international scientific studies about women's sleeping position during pregnancy. These case controlled and cross-sectional studies have shown that women who go to sleep on their back have a higher chance of having a stillborn baby compared women who go to sleep in another position.1,2,3,4
The studies found that the chance of having a stillborn baby ranged between 2.5 to 8 times greater for women who went to sleep on their back. The research suggests that 1 in 10 stillbirths occurring in late pregnancy (> 28 weeks’ gestation) could potentially be avoided if women did not go to sleep on their back during this time.1,2,3,4
A 2019 meta-analysis using all the available world-wide data on the topic demonstrated an adjusted odds ratio of 2.63 (95% CI 1.72-4.04, p<0.0001) for late stillbirth in women who reported a going-to-sleep supine position5. Going to sleep on the left or right side appeared equally safe5.
Studies using magnetic resonance imaging (MRI) show that in late pregnancy, mothers lying supine put pressure on the inferior vena cava, which can reduce the blood flow by 80%. The pregnant woman’s aorta is also partly compressed in this positon6,7 which reduces the blood flow and oxygen delivery to the pregnant uterus, placenta, and fetus. Other studies have shown that the maternal supine position reduces fetal movements and increases fetal heartrate decelerations8.
It is important to discuss the recommendation on sleep position with women before 28 weeks’ gestation. Women report a willingness to change their going-to-sleep position to reduce the risk.
NSW Health has developed new resources for health professionals (poster) and for pregnant
women (flyer) to support this recommendation. Alternative versions of these resources are available for Aboriginal women. Health professionals are encouraged to display the posters in their maternity facilities and distribute the flyers to pregnant women.