"Try to provide yourself with what you consider a good environment. The less stress, the better," advised lead researcher Pablo Nepomnaschy, a postdoctoral fellow at the National Institute of Environmental Health Sciences of the National Institutes of Health in Research Triangle Park, N.C.
His team published its findings in this week's issue of the Proceedings of the National Academy of Sciences.
The NIH team evaluated 61 women over 12 months, collecting each woman's urine three times a week to check for pregnancy status and levels of cortisol, a stress-linked hormone.
"This study is special in the sense that we include cortisol data," said Nepomnaschy, He added that they did this testing very early in the pregnancy because "most pregnancy losses take place in the first three to four weeks after conception."
Of the 61 women, 22 got pregnant. Nine carried to term and 13 miscarried. Women with increased cortisol levels during the first three weeks of pregnancy were 2.7 times more likely to miscarry, the researchers found.
In all, miscarriages occurred in 90 percent of pregnancies in which the women had increased cortisol levels and in 33 percent of those with normal cortisol levels.
Nepomnaschy said it's unclear why a boost in cortisol might raise miscarriage risks, but he offered a hypothesis: "The body might interpret that [increased cortisol level] as conditions deteriorating, and maybe that might trigger an abortion mechanism."
The women studied were all residents of a rural area of Guatemala. "This population is more alike than any population in the United States," Nepomnaschy said, explaining that he was trying to get a sample of women who were similar in lifestyle, ethnicity and culture to rule out other factors linked to miscarriage. The women studied had similar diets and activity levels, and were all of the same ethnicity.
Another expert, Dr. Mary Stephenson, an obstetrician-gynecologist who runs the Recurrent Pregnancy Loss Program at the University of Chicago, said, "It's an intriguing article. Certainly more research is needed. But it is a potential mechanism by which miscarriage may occur."
Other studies have looked at the cortisol/miscarriage link, Stephenson said. "The results have been conflicting. There are some studies in animals that suggest that stress increased the risk of miscarriage. And doctors have long suspected that stress does the same in people."
About 15 percent of recognized pregnancies end in miscarriage, according to the March of Dimes. But Stephenson said that statistic usually includes pregnancies that made it to six weeks. "When you count the ones that occur before six weeks, up to half of pregnancies end in miscarriage," she noted.
The best advice for women trying to get pregnant is to de-stress your life before you conceive, she said.
"I talk about this a lot with my patients," Stephenson said. "I recommend that before they get pregnant, they take a serious look at their lifestyle."
And that includes getting enough sleep, so fatigue isn't an issue. "Fatigue is a type of stress," Stephenson said.
More information
To learn more about miscarriage, visit the March of Dimes.
