Maternal Sleep Position

Maternal supine sleep in the third trimester has been associated with an increased rate of stillbirth and small for gestational age babies. Pregnant women should be informed of this correlation and encouraged to go to sleep on their side after 28 weeks of gestation.

Background

Five case-control studies and an individual participant data meta analysis have found an association between stillbirth and maternal supine sleep position in the 3rd trimester. The initial studies indicated the left lateral was the preferred position, however, more recent studies indicate that going to sleep in any position other than supine is equally advantageous for reducing the risk of stillbirth. For babies who are growth restricted and their mother slept in a supine position in the third trimester, the odds ratio for stillbirth increased to 15x more than babies who are not growth- restricted and whose mothers slept in a non-supine position.

The mechanism behind these findings is believed to be the result of decreased blood return with increasing weight of the gravid uterus. A decrease in maternal cardiac output and subsequent reduction in uterine perfusion has been documented when the mother is supine. Of note, the going-to-sleep position is associated with stillbirth, but the waking-up position is not.

NICE Guidelines published in 2021 recommend educating all pregnant women on the association of supine sleep with stillbirth. Unfortunately, reports indicate that less than 20% of health professionals routinely offer information to patients about sleep position.

Recommendations

• Provide verbal and written information about safe sleep practices to all pregnant women and families by 24 weeks
• Encourage pregnant women to go to sleep on their side in the third trimester
• Teach pregnant women that this sleep position increases blood flow to their baby
• Ask about sleep position at each encounter in the third trimester
• Suggest a wedge, tennis ball, or similar tool to support women who have difficulty sleeping on their side