Cortisol is a hormone that is released when we are under stress and its high levels have been linked to early miscarriages in women. It has been found that women who are under a lot of stress and who have elevated urinary cortisol levels are three times likely to miscarry in the first three weeks of pregnancy.

A study that provided this link included women between age 18 and 34 years and there urine samples have been taken three times a week for a whole year. Cortisol levels have been checked even before they conceived. The study results showed that the incidence of miscarriage was so high in women who had elevated levels of cortisol. It was 90% comparing to 33% in women whose cortisol levels were normal.

It is still not known how high cortisol levels induce miscarriage and bigger and longer trials are on the way to prove some of the existing theories. It is thought that the brain perceives high cortisol levels as a hostile environment for a fetus to develop and signals the body to prevent it from happening. Another theory is that high cortisol levels induce miscarriage directly but final results are yet to come.