Lying on Back in Third Trimester of Pregnancy May Up Risk of Stillbirth – Study

Much evidence has come to light showing how much maternal position is important for the baby’s health. Expectant moms who lie on their backs in the third trimester of pregnancy may have a greater risk of stillbirth, new research suggests.

According to the research, pregnant women lying lying face up during the last three months of pregnancy may place stress on the unborn baby, which could elevate the risk of stillbirth.

Researchers at the University of Auckland in New Zealand have found that lying down on their back while pregnant can change the heart rate and activity state of the fetus possibly due to receiving lower levels of oxygen.

This finding showed that “maternal position has a significant relationship with both foetal behavioural state (a measure of fetal health) as determined by features of foetal heart rate and its variability.”

To reach their findings, lead investigator Peter Stone, professor of maternal foetal medicine at the University of Auckland, and colleagues studies 29 healthy pregnant women in their third trimester. The team monitored the fetal and maternal heart rate while changing and maintaining one of four maternal positions for 30 minutes at a time.

The four positions included lying on the left side, lying on the right side, lying on the back but propped up at a 30-degree angle with a pillow, and lying flat with a pillow. The fetal behavioural state was recorded for each maternal position. All the participating women were followed until delivery and all gave birth to healthy babies.

“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 explained.
He added, “We have only looked at the effect of maternal positions for a short period of time while the mother is awake. Further research is needed to see the effect of staying in certain maternal sleeping positions overnight.”

Commenting on the current study outcome, Hannah Knight, from the Royal College of Obstetricians and Gynaecologists (RCOG), said: “This is not the first piece of research to suggest a possible link between a mother’s sleeping position and stillbirth risk. This study suggests that in late pregnancy, the heart rate of a foetus can change when a mother’s position changes.

Knight further said: “It is important that women are not unnecessarily alarmed by the results of this small study of 29 women, none of whom had a stillbirth. Instead, it measures the incidence of babies in a sleep-like state, which has little evidence of any association with hypoxia, brain damage or stillbirth.

“It is not possible to draw a firm link between maternal position and stillbirth risk from this study and further robust research is needed,” she concluded.

The latest study findings are published in The Journal of Physiology.