An Auckland University study published in the British Medical Journal suggests pregnant women can halve their risk of having a late stillbirth by sleeping on their left hand side.
PhD student Tomasina Stacey investigated what sort of factors contribute to stillbirths for her doctorate project.
A total of 155 Auckland women who gave birth to a stillborn baby were interviewed.
The results showed that women sleeping on their left side on their last night of pregnancy had a 1.96 in 1000 chance of giving birth to a stillborn baby.
The risk doubled to 3.93 in 1000 for women sleeping on their right side or back.
Researchers believe that position may restrict blood flow to the baby.
However, Professor Lesley McCowan, of Auckland University, says further work is needed before health advice is updated.