A New Zealand-led international study published today provides the strongest evidence yet that women can more than halve their risk of stillbirth by going to sleep on either side during the last three months of pregnancy.

This mega study (known as individual participant data meta-analysis) has also confirmed the risk of stillbirth associated with sleeping on the back applies to all pregnant women in the last trimester of pregnancy.

Risk factors

In New Zealand, stillbirth is defined as the loss of a baby after 20 weeks of pregnancy. An estimated 2.64 million babies die before birth globally each year, and around 300 babies are stillborn in Aotearoa New Zealand each year. About one in every 500 women in New Zealand will experience the tragedy of a late stillbirth and lose their baby during or after 28 weeks of pregnancy.

We have analysed all available data worldwide from five previous studies, including our earlier research, the 2011 Auckland Stillbirth Study, which first identified a link between mothers’ sleeping position and stillbirth risk. The main finding in the mega study, which included information from 851 bereaved mothers and 2,257 women with ongoing pregnancies, was that going to sleep lying on the back (supine) from 28 weeks of pregnancy increased the risk of stillbirth 2.6 times.