Despite those beliefs, relatively few of the women surveyed blamed mothers for a poor pregnancy outcome. Ten percent suggested pregnant women are responsible for their miscarriages, and 3 percent said mothers should be blamed for their babies' birth defects. Women with less formal education were more likely to hold mothers responsible for bad pregnancy outcomes.
The recent Ohio State University study points to the persistence of folklore surrounding pregnancy despite advances in medical interventions and evidence that most miscarriages and defects result from circumstances beyond a woman's control, said study author Jonathan Schaffir, a clinical assistant professor of obstetrics and gynecology at Ohio State.
"The survey shows that a sizable proportion of the population believes maternal thoughts and actions contribute to adverse fetal outcomes – but despite these feelings, few assign responsibility to the mother,” Schaffir said. “I think it's kind of amazing that people out there still believe that a pregnant woman seeing something frightening could cause her baby to have a birthmark. That was an 18th-century belief and it's still circulating, even today.
"I had a call not long ago, before Halloween, from a pregnant woman asking if it would be OK to go to a haunted house. I told her it was fine."
The study appears online in the journal Archives of Women's Mental Health.
Most miscarriages result from genetic or chromosomal abnormalities in the fetus, or from medical complications relating to hormonal imbalances or problems with the uterus or placenta, Schaffir noted.
"Most of these things are beyond anyone's control and can happen to anyone," he said. "In general, minor day-to-day experiences don't have an effect on whether a pregnancy is successful or not."
Exceptions, of course, would include the abuse of alcohol or drugs during pregnancy, which can lead to complications, he said.
Schaffir surveyed 200 women by circulating a questionnaire in the waiting area of a Midwestern obstetrics and gynecology clinic. He asked respondents to rate their level of agreement with common folk beliefs about prenatal influences on fetal outcomes, and whether or not respondents had a history of an adverse pregnancy outcome.
The folkloric beliefs the participants considered included whether a pregnant woman's stress, bad mood, viewing of upsetting TV programs or attending upsetting events, excessive exercise, unfulfilled food cravings, or exposure to ugly or frightening sights could have a negative effect on her unborn baby. An additional item for consideration was whether a baby's appearance is determined at conception. Two final entries gauged whether respondents thought miscarriages and birth defects should be blamed on mothers.
Six percent of respondents thought a mother's unfulfilled food cravings could have an adverse effect on a fetus and 5 percent believed a pregnant woman's exposure to a scary sight could hurt her unborn baby. Thirty-eight percent of the women surveyed believed that a baby's appearance is determined at conception. More than three-fourths (76 percent) of women believed stress could cause a bad pregnancy outcome.
Schaffir expected women who had miscarried or delivered a baby with serious birth defects to be more inclined to believe that they had somehow contributed to their misfortune. But the survey results did not support his expectation. Instead, the level of a woman's education appeared to affect her belief system, with a lower level of education resulting in a higher likelihood of blaming mothers for bad pregnancy outcomes.
"Women with less education were more likely to think problems were a mother's fault. This isn't necessarily because women learn more about pregnancy during formal education, but reflects that women who have pursued higher education might read more and rely on more stringent sources for information about what they choose to believe. They might be more scientifically guided," he said.
Education levels among respondents included some high school (33 women), high school graduate (46), some college (59), college graduate (40) and graduate school (19). Women with less education were also more likely to believe that stress can adversely affect pregnancy.
The pregnancy history of survey respondents appeared to have no bearing on beliefs in any but two areas. Women with no history of bad pregnancy outcomes were more likely to believe a bad mood or a fright could lead to birth defects or miscarriages, suggesting to Schaffir that women who had received medical care for an adverse pregnancy outcome were provided with more fact-based explanations for what had happened to them.
The mere existence of these beliefs suggests there is an opportunity for education in the exam room, Schaffir said.
"I do think there is room for educating women more, particularly those who have less formal education, to prevent them from feeling any guilt in association with their pregnancy," he said. "Health care providers can reassure patients that these 'old wives' tales' should not contribute to any feelings of personal responsibility."
The survey respondents' belief that stress can affect pregnancy outcomes mirrors more conventional societal beliefs as well as a growing body of research about the effects of stress on health, Schaffir noted. But because he was gauging opinions and not facts about pregnancy, he did not explore that finding.
"A majority of people agree that stress can contribute to a bad outcome, and for more long-term behavioral disorders, it's not all that farfetched. But I was studying what people believe rather than what actually causes poor outcomes," he said.