Stress/Prembirth

By Jacqueline Stenson

NEW YORK (Reuters Health) - While studies on the effects of stress during pregnancy have yielded conflicting results, the latest report finds that it may raise a woman's risk of premature delivery.

Pregnant women who said they were experiencing high levels of stress from events such as marital separation, problems with in-laws or issues at work were 80% more likely to have a preterm delivery than those who reported low stress levels.

Overall, there were 71 preterm births and 402 full-term births among women reporting high stress, compared with 39 preterm births and 416 full-term births in the low-stress group, according to findings published in the January 1st issue of the American Journal of Epidemiology.

Study author Dr. Nancy Dole, associate director of the Carolina Population Center at the University of North Carolina in Chapel Hill, said she wasn't surprised by the finding because other studies on this issue, though not all, have suggested such an association.

Dr. Peter Heyl, an associate professor of obstetrics and gynecology at Eastern Virginia Medical School in Norfolk, Virginia, said he believes stress can increase a woman's risk of premature delivery, but just how much is unclear because studies have found varying degrees of impact.

"I think stress is a factor in a lot of pregnancies that end up with a preterm delivery," he said in an interview.

Still, the majority of pregnant women who are under stress will not have a premature delivery, Heyl emphasized.

Among those most at risk are women in low socioeconomic groups who may get inadequate prenatal care and have constant worries about critical issues such as paying rent and putting food on the table, he said.

"Stress is a fight-or-flight kind of phenomenon," Heyl said, explaining that pregnant women under stress may have increased steroid secretions in the womb that can stimulate cellular receptors that control uterine contraction and relaxation. "Chronic stress could over-stimulate those receptors," he said.

The new study involved 1,962 pregnant women who were being treated at two prenatal clinics in North Carolina. In addition to their medical exams, the women were instructed to complete and mail in a survey that asked various questions about their psychological state, stressful life events, social support and other issues that might impact their pregnancies.

A total of 231 women delivered their babies prematurely, defined as before 37 weeks of pregnancy.

Results also showed that women who felt a lot of anxiety about their pregnancies, including those who experienced vaginal bleeding or had a history of miscarriage or other pregnancy problems, were twice as likely to deliver prematurely than women reporting low anxiety. But even women in the high-anxiety group who did not have identifiable underlying medical issues still were at increased risk for preterm delivery. In addition, women who perceived racial discrimination in their lives were 40% more likely to have a preterm birth than those who did not feel discriminated against.

So what should stressed-out mothers-to-be do?

"There's a general feeling that if women recognize the stress in their lives and can do some stress reduction during pregnancy, that's probably a good thing," Dole told Reuters Health. "But will it prevent a preterm birth? We're not in a position to say that."

Though the study linked stress with premature delivery, it did not find that having strong social support--such as having someone to talk over problems with or take them to see the doctor--substantially decreased the risk. "Our findings are consistent with some of the research showing that there's little effect for social support," Dole said. "It may be that certain kinds of support are more important than others."

Heyl said he regularly counsels stressed patients to find ways to relax.

"I recommend any relaxation technique, short of wild dancing till 3 in the morning and drinking, of course," he said. Yoga in pregnancy, he added, is "wonderful."

SOURCE: American Journal of Epidemiology 2003;157:14-24.