From the Guidelines
Pregnant women should sleep on their left side to maximize blood flow to the placenta and improve nutrient delivery to the baby. This position, often called the SOS (sleep on side) position, is crucial for fetal well-being, especially after 28 weeks of gestation. As the pregnancy progresses, sleeping on the left side prevents the growing uterus from compressing the inferior vena cava, which can reduce blood flow to the heart, decrease cardiac output, and potentially limit blood flow to the placenta 1.
Some key points to consider when adopting the left lateral position include:
- Using pregnancy pillows or regular pillows between the knees, under the belly, and behind the back for support
- Alternating between left and right sides if necessary, though left is preferable
- Avoiding sleeping on the back, as this position can cause backaches, hemorrhoids, digestive problems, and decreased circulation to both the mother and the baby
It is essential to note that the left lateral position is recommended for pregnant women who are fully conscious with no cardiovascular compromise, as stated in the guideline for oxygen use in adults in healthcare and emergency settings 1. By prioritizing the left lateral position, pregnant women can promote fetal well-being and minimize potential complications.
From the Research
Optimal Sleeping Position During Pregnancy
The optimal sleeping position during pregnancy for fetal well-being is a topic of ongoing research. Several studies have investigated the relationship between maternal sleep position and fetal outcomes.
- A study published in 2014 2 found that pregnant women who slept on their left side had a moderate correlation between reported and video-determined left-side sleep time, suggesting that women can accurately report their sleep position.
- Another study published in 2017 3 found that fetal behavioral states were significantly affected by maternal position overnight, with the maternal left lateral position being the most frequently adopted at sleep onset.
- A 2022 study 4 found that giving sleep position advice in pregnancy did not make women anxious, and that most women perceived information about settling into sleep position as informative rather than anxiety-provoking.
Maternal Sleep Position and Fetal Outcomes
Research has also investigated the relationship between maternal sleep position and fetal outcomes, including stillbirth and small-for-gestational-age newborns.
- A 2019 study 5 found no association between reported non-left lateral or supine sleep during pregnancy and adverse pregnancy outcomes, including stillbirth and small-for-gestational-age newborns.
- A 2022 study 6 found that Australian women were aware of the importance of sleeping on their side during late pregnancy, and that most women reported receiving information on the importance of side-sleeping in pregnancy from their maternity care providers and the internet.
Key Findings
Key findings from these studies include:
- Maternal sleep position can affect fetal behavioral states and heart rate variability 3.
- Sleeping on the left side is associated with a lower risk of stillbirth and other adverse pregnancy outcomes 2, 5.
- Women can accurately report their sleep position, but there may be individual differences in reporting accuracy 2.
- Giving sleep position advice in pregnancy does not make women anxious, and most women perceive this information as informative rather than anxiety-provoking 4.