Expectant mothers who sleep on their backs during late pregnancy are more at risk of a stillbirth, a new study warns.
Around one in 227 births in the U.K. end in stillbirths, and researchers believe it could be down to women sleeping in this particular position as it may cause more stress which in turn leads to a reduction in oxygen consumption.
Scientists led by Professor Peter Stone, of the University of Auckland, monitored 29 healthy women with child and their unborn babies during the third trimester of pregnancy. All the ladies were at low risk of complications and between 35 and 38 weeks pregnant.
They were given four positions to lie in; lying flat, lying with their back propped up by 30 degrees and lying on their ride or left side, all of which were allocated randomly and included a pillow under the head.
After lying down for 30 minutes health experts monitored the foetus for heart rates and activity level. The babies whose mums lay flat on their backs suffered more stress, which led to what researchers describe as a sleep-like state involving lower activity and less oxygen consumption.
Furthermore, the little ones were five times more likely to end up in this state when mothers were on their backs rather than lying on their left sides.
“Our controlled study found that lying on your back can add extra stress to the baby, contributing to the risk of stillbirth. The risk is likely to be increased further in women with underlying conditions,” Professor Stone said.
“Maternal position has a significant relationship with both foetal behavioural state as determined by features of foetal heart rate and its variability,” authors added. “The supine position (lying face up) maybe disadvantageous for foetal wellbeing and in compromised pregnancies may be a sufficient stressor to contribute to foetal demise.”
However, Professor Stone notes more research is needed to find out what happens when women sleep in certain positions overnight, as they had only monitored the results of a short period of time.
Results were published in the Journal of Physiology.
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