when should you start sleeping on your side when pregnant

You’re generally advised to start going to sleep on your side by around 28 weeks of pregnancy (the start of the third trimester) and to keep doing this for every sleep, including naps.

Why side sleeping matters

• From about 28 weeks, lying flat on your back can let the growing uterus press on major blood vessels, which may reduce blood flow and oxygen to the baby.

• Research and national campaigns in several countries now recommend “go to sleep on your side from 28 weeks” to lower the risk of stillbirth in late pregnancy.

• It usually does not matter whether you choose left or right side; both are considered safe, although some professionals slightly prefer the left for optimal blood flow.

When to start changing position

• Many clinicians phrase the advice as: “By 28 weeks, start every sleep on your side,” even if you naturally move in your sleep.

• Some people begin practicing side sleeping earlier (late first or second trimester) simply to get used to it and because it often feels more comfortable as the bump grows.

• If you wake up on your back, you don’t need to panic; just roll onto your side and go back to sleep. The key is the position you fall asleep in, because that tends to be the longest-held position.

Left vs right side

• Evidence does not show a clear difference between left and right side in terms of stillbirth risk, so either side is acceptable.

• Many brochures still suggest the left side as a slight “best” option because it may help kidney function and blood flow, but switching sides for comfort is completely fine.

Practical tips to switch to side sleeping

• Use:
  • A pillow between your knees
  • A small pillow under your bump
  • A firm pillow behind your back to discourage rolling flat.

• Pregnancy pillows (C‑shaped or U‑shaped) can help keep you comfortably on your side through the night.

• If full side-lying feels hard at first, a slight tilt (e.g., leaning back on a pillow “wedge”) still reduces pressure on major blood vessels compared with lying completely flat on your back.

Safety note

• It is usually safe to sleep on your stomach early in pregnancy, but it tends to become uncomfortable as the uterus grows, often sometime in the second trimester.

• For any history of high blood pressure, growth issues, or previous stillbirth, your own clinician may give more tailored, sometimes stricter, sleep-position advice, so checking directly with your midwife or doctor is important.

Bottom note: Information gathered from public forums or data available on the internet and portrayed here.