A study that examined cortisol (a stress induced hormone) levels in pregnant women found that those who exhibit signs of stress are three times more likely to miscarry during the first three weeks of the pregnancy. The researchers, from the University of Michigan, speculate that the body may recognize the elevated cortisol levels as a signal that conditions are not right for pregnancy. Previous studies have reported that up to 90 percent of all conceptions result in miscarriage. This high figure reflects the fact that most women notice they are pregnant about six weeks after conception, but most miscarriages are known to happen during the first three weeks of pregnancy.
It was this critical three week initial period of pregnancy that researcher Pablo Nepomnaschy decided to investigate. "The only way to capture the first three weeks of pregnancy is to begin collecting their urine from before they become pregnant. That is extremely labor intensive and expensive," he explained.
In the study, Nepomnaschy found that 90 percent of the women with elevated levels of cortisol miscarried during the first three weeks of pregnancy, compared to 33 percent of those with normal levels. "Maybe increased cortisol is understood by the body as a cue that the context is uncertain, changing, or the quality of the environment is deteriorating," Nepomnaschy said. "The body's response is to stop any extra activity and go back to its most basic functions."
Previous studies that focused on later pregnancy stages did not find an association between elevated cortisol and miscarriage and Nepomnaschy believes that stress may be more likely to lead to loss during the earliest stages of pregnancy, while the embryo is just beginning to develop.
It was unclear from the study whether cortisol is directly involved with miscarriage, or if it signals some other mechanism in the body that triggers it. However, the results are consistent with a 2004 study in which Nepomnaschy found that elevated cortisol levels were associated with lower progesterone levels (a hormone that prepares the uterus for the implantation of the fertilized ovum). "The two pieces of research are consistent in this sense," Nepomnaschy concluded.
Source: University of Michigan
