It is generally safe to sleep on your back during the first trimester of pregnancy. However, after about 20 weeks (midway through pregnancy), sleeping on your back is not recommended because the growing uterus can put pressure on major blood vessels, such as the inferior vena cava, reducing blood flow to the fetus and the mother's heart. This can cause low blood pressure, dizziness, nausea, and potentially harm fetal growth. For this reason, health experts advise pregnant people to sleep on their side, preferably the left side, from the second trimester onward as it promotes better circulation and is safer for both mother and baby. If you do wake up on your back during pregnancy, it usually isn't harmful if only for a short time, but it is best to return to a side position.
Summary of safe sleep positions in pregnancy:
- 1st trimester: Sleeping on back is generally safe.
- After 20 weeks: Avoid back sleeping; side sleeping, especially left side, is recommended.
- Side sleeping supports better blood circulation and reduces risk of complications.
If uncertain or if changing sleep positions is difficult, pregnant individuals should consult their healthcare provider for personalized advice. This guidance is based on research showing that back sleeping in later pregnancy could increase risks like stillbirth and low birth weight, though more studies are ongoing to solidify these findings.
