University of South Australia study finds link between stillbirth and sleep
An international study investigating maternal sleep practices has found sleeping more than nine hours a night is linked to late stillbirth.
Researchers from Australia, New Zealand, the United States and the United Kingdom surveyed 153 women who had experienced a late stillbirth (after 28 weeks of pregnancy) as well as 480 women with an ongoing third trimester pregnancy or who had recently delivered a live baby.
The study, published in the journal Birth, revealed that extended periods of undisturbed sleep in pregnancy was associated with late fetal death independent of other risk factors.
Principal researcher Associate Professor Jane Warland from the University of South Australia’s School of Nursing and Midwifery said the findings suggest disturbed sleep could be a protective factor during pregnancy.
“Until now, maternal sleep has been overlooked as a potential risk factor for stillbirth, but these study findings warrant further investigation,” said Assoc Prof Warland.
“Blood pressure reaches its lowest point during sleep but when someone wakes up there is a surge in the nervous system activity that causes increases in blood pressure. This is important because low blood pressure has been linked with fetal growth problems, pre-term birth and stillbirth.”
Online data was collected in a case-controlled study from participants who had experienced a stillbirth within 30 days of the survey. The study investigated changes in maternal sleep practices before, in the last month and on the last night of pregnancy.
“It’s a unique finding but supports existing research on maternal sleep that has shown women are at less risk if they wake up multiple times during the night,” said Assoc Prof Warland.
The World Health Organization estimates there were 2.6 million stillbirths worldwide in 2015. The established risk factors for stillbirth include advanced maternal age, obesity, smoking and conditions such as diabetes and pre-eclampsia.
Assoc Prof Warland said it was unusual for pregnant women to sleep for more than nine hours per night, particularly towards the end of their pregnancy.
“Another hypothesis we considered was that women who are sleeping more than nine hours solidly are doing so because they babies aren’t very active,” said Assoc Prof Warland.
“Normally the baby would be moving and naturally waking a mother during sleep, which is a potential avenue for future research.”
Assoc Prof Warland will continue her research on late stillbirth risk factors, with her next study investigating the significance of maternal sleep positioning during pregnancy.
“The unborn baby is developing for a third of its life while the mother is asleep, sleep is an important concept to get a handle on to fully understand stillbirth risk factors.”