Sept. 8, 2000 -- Sudden, extremely stressful events that happen in the first few weeks of pregnancy, like losing an older child, may put some women at risk for having a baby with birth defects. But for a pregnant woman going through a traumatic time, there are also ways to cope with the situation that could help.
When traumatic or emotional situations occur, levels of the body's stress hormones increase. High levels of one stress hormone in particular, cortisone, has previously been linked to birth defects in animals.
Researchers from Denmark report in the Sept. 9 issue of The Lancet that women who experience severe emotional stress in the first trimester of pregnancy, such as the death of a child, are more likely than women who do not experience that type of stress to have a baby with defects of a particular type, mainly heart defects or cleft lip, cleft palate, or both. Those exposed to the unexpected death of a child were more likely to deliver babies with birth defects involving other organs as well.
The authors say the findings suggest that severe stress can directly affect tissues and organs at a crucial time in a baby's development. It is in the first three months of pregnancy that the baby's organs are forming.
Suzan Carmichael, PhD, a researcher with the California Birth Defects Monitoring Program, stresses, though, that the study is "very preliminary." She says the study confirms previous research and should be of help to others who are trying to show how response to stress results in actual changes in the body's levels of substances that may ultimately be harmful to a developing baby.
She also points out that other factors related to how the mother deals with a stressful situation could be involved in increasing risk of birth defects. For example, a mother who copes with an overwhelmingly stressful situation by eating poorly, smoking cigarettes, or drinking alcohol can significantly increase the risk to her child.
Study author Dorthe Hansen and colleagues examined medical records of over 3,300 women who reported severe stress while pregnant or just prior to pregnancy and nearly 20,000 women who reported no stress during or prior to pregnancy.
The unexpected death of an older child during the first third of pregnancy when the baby is forming was the situation most likely to be associated with birth defects. When that happened, the risk of abnormalities -- most commonly heart defects and cleft lip or palate -- was more than eight times greater and the risk of other types of birth defects was nearly four times greater
The highest rate of birth defects in women (those who reported unexpected death of a child early in pregnancy) was nearing 5%; for other sudden stressful events it was lower. By comparison, in the group of women unexposed to extreme stress, the rate of birth defects was near 4%, emphasizing that the number of women in either group who had affected babies was small.
Other researchers, such as Carmichael, urge caution in interpreting the study, saying the events defined as stress in the study were severe -- and fortunately, rare -- events. Nonetheless, the study supports the notion that other birth defects that are not caused by genetics or exposure to harmful substances may be stress induced.
Donald R. Mattison, MD, medical director of the March of Dimes in White Plains, N.Y., says some researchers believe there are probably internal "thresholds" above which levels of stress or exposure to other potential dangers can cause damage to a developing fetus. Below those thresholds or levels of stress, however, no damage occurs.
Mattison says the study's finding that more than 95% of women exposed to terribly stressful situations early in pregnancy did not have a baby born with birth defects should be reassuring. And, the finding shows that it is not necessarily the stress itself, but the reaction of the mother's body to the stressful event that is a determining factor.
"Stress is a life experience that is somewhat difficult for us to quantify," Mattison says. He tells WebMD the study's conclusions would be more valuable if researchers could show a link between certain stressful events and specific changes in the mother's body.
"It might be that those individuals at greatest risk of [birth defects] were those that were the most profound responders to stress. It doesn't necessarily have to be a behavioral response, but a biochemical response," Mattison says.
For pregnant women experiencing extreme stress, remember, there is help, and women going through stressful times should contact their doctor and seek out resources in their community.