One in eight babies born in the United States each year will be premature [source: CDC]. In medical speak, this means that he or she will be born at less than 37 weeks gestation. There are lots of different reasons why babies are born prematurely, but many researchers believe that women who experience high levels of stress while pregnant are at high risk for experiencing a preterm birth. There's a reason why pregnancy is supposed to last 40 weeks -- babies born before this often do not have fully formed organs. The earlier a baby is born, the greater risk the child has of experiencing anything from minor breathing problems to lifelong diseases such as cerebral palsy.
Stress normally causes our brains to secrete hormones, such as corticotropin-releasing hormone (CRH). In pregnant women, CRH also helps to regulate the length of a pregnancy, and the amount naturally rises near the end of the third trimester to stimulate contractions. A study published in the American Journal of Obstetrics and Gynecology in 1999 (and subsequent studies by the same team) revealed that women who delivered prematurely not only had very high levels of CRH early on in pregnancy, but they also reported high levels of stress.
Next, find out why stress can even be related to one of the worst things a woman can experience while pregnant.