Research shows that going to sleep on your side from 28 weeks of pregnancy halve your risk of stillbirth compared with sleeping on your back. Why should I go to sleep on my side? Lying on your back in the last three months of pregnancy (from 28 weeks) presses on major blood vessels which can reduce blood flow to your womb and oxygen supply to your baby. Is it best to go to sleep on my left or right side? You can settle to sleep on either the left or the right side – any side