Jan. 12, 2000 (Baltimore) -- Everyone wants to avoid stress. Now two studies in the January issue of the journal Epidemiology give women who have just become pregnant even more reason to steer clear of tension. The studies showed that women who experience mental or physical stress around the time they become pregnant or for the first few months of pregnancy may be at increased risk of either miscarriage, also called spontaneous abortion, or of having an infant with a birth defect .
"Our study shows a modest association between stressful events and congenital anomalies [birth defects]," says Suzan Carmichael, PhD, lead author of one of the papers, in an interview with WebMD. "It's still somewhat preliminary given the limited number of questions we asked about stress, but it does point the way for future studies," says Carmichael, an epidemiologist with the March of Dimes/California Birth Defects Monitoring Program in Emeryville, Calif.
Carmichael and colleagues collected data from mothers who had had an infant with one of several types of birth defects and whose pregnancies ended during 1987-89 in California. They compared this data with that from mothers who delivered healthy infants during the same time period.
Mothers were interviewed by telephone and asked about stressful exposures during the periconceptual period, defined as one month before conception until the end of the third month of pregnancy. "Questions about stressful events included deaths of anyone close to the mother, separation or divorce in the mother or someone close to her, or job loss in the mother or someone close to her during the periconceptual period," says Carmichael. "Stressful events during this period were associated with a moderate increase in congenital anomalies."
Dr. Paul Blumenthal, MD, associate professor of obstetrics and gynecology at Johns Hopkins University in Baltimore, who gave objective comment on the papers to WebMD, says, "This study was retrospective and therefore subject to recall bias. Women who have had bad outcomes have been shown to be much more likely to recall negative events during pregnancy than those with good outcomes. There are also some serious statistical problems with this paper."
The second paper looked at physical strain taking place during the time of implantation in women experiencing their first pregnancy. Neils Henrik Hjollund of the Aarhus University Hospital in Copenhagen, Denmark, and lead author of the paper writes, "The analysis included 181 pregnancies. ... Physical strain around the time of implantation was associated with later spontaneous abortion."
Women participating in the study were asked to keep a special diary during the time they were trying to get pregnant. Information on sexual intercourse, vaginal bleeding, and physical activity and strain was recorded. An association between increased physical strain around the time of implantation and spontaneous abortion was seen.
Dr. Carl Weiner, MD, professor of obstetrics and gynecology at the University of Maryland School of Medicine, commented on this study for WebMD. He says, "This study is provocative because of the prospectively kept diary. Still, it's difficult to propose a mechanism whereby someone would be at increased risk for adverse implantation because of physical strain. The possibility can't be excluded but I'm not convinced by this study."
- A new study shows that women experience stress around the time of conception are more likely to deliver babies with birth defects or miscarry, compared with those who do not experience stress.
- One problem with the study is that it was retrospective, and women who have bad outcomes are more likely to remember the negative events that occurred during pregnancy, according to one expert.
- A second study on pregnancy showed that physical strain around the time of implantation increased the risk of spontaneous abortion.