Mom’s stress can put unborn baby at risk
Reported August 12, 2008
If you’re pregnant, think twice before taking on an extra project at work. Severe stress, even in the short term, might almost double the risk of having a stillbirth — although stillbirths are rare.
Stress has been linked to premature birth, high blood pressure and other health problems associated with stillbirths. Now, Kirsten Wisborg from the Aarhus University Hospital in Denmark and colleagues have shown that stress increases the risk even when women don’t have these problems.
“We don’t yet know for sure whether stress may directly cause stillbirth, but our results are enough for doctors and midwives to be concerned,” she says.
The researchers analyzed questionnaires filled in by more than 19,000 women during the last three months of pregnancy. In one section, the survey asked them whether they were unable to concentrate or handle problems, had lost self-confidence or felt unhappy or unworthy, compared to just a few weeks before.
Based on their answers, a third of the women scored highly for stress. The researchers then monitored how many women had stillbirths.
They found that in the high-stress group, 29 of the women — or 0.5 percent — had stillbirths after 28 weeks, whereas in both the intermediate and low-stress groups, it was about 0.3 percent.
The results held up even when women with high blood pressure, premature delivery or other relevant health problems were excluded from the analysis.
Although the figures are small, Wisborg says that difference is significant: “Thankfully, stillbirth is a rare event. But we still do not know what causes it, and any clues we find can help us reduce the risks.”
Studies in monkeys suggest that stress hormones such as adrenalin might be reducing blood flow to the placenta, which could restrict oxygen supply to the fetus. Although the effect is likely to be small, if the baby has any other problems, stress could “tip the balance,” says Andrew Shennan, an obstetrician at St. Thomas’ Hospital in London and spokesman for baby charity Tommy’s. The next step, he says, is to reduce stress in pregnant women and see if that reduces stillbirths.
But Vivette Glover, a perinatal psychobiologist at Imperial College London, says that people should start changing their behavior now. The stillbirth results are the latest in a growing list of ways that stress during pregnancy might harm babies, which includes cognitive problems in children and miscarriage.
“People looking after pregnant women should pay much more attention to their emotional health, and employers should be open to flexible working hours,” says Glover.
The current study only measured the effect of recent increases in stress. If chronic stress were taken into account, more of the stillbirths may have been linked to stress, says Wisborg.