A recent study in Finland found that women who experienced high levels of anxiety early in pregnancy were three times as likely as less anxious women to develop pre-eclampsia, a pregnancy-related form of high blood pressure that can result in poor fetal growth and other problems.

Babies who are born prematurely are often of low birth weight. However, studies also suggest that babies of women who suffer from high levels of stress and anxiety are more likely to be born with low birth weight even when born at full term. It appears that corticotropin-releasing hormone (CRH) or other stress-related hormones may constrict blood flow to the placenta, so the fetus may not receive the nutrients and oxygen it needs for optimal growth.

CRH, which is produced by the brain and the placenta, is closely tied to labour. It prompts the body to release chemicals called prostaglandin, which trigger uterine contractions. CRH also is the first hormone our brains secrete when we are under stress. Researchers continue to explore the possibility that women who experience high levels of stress early in pregnancy have elevated levels of CRH that set their placental clock for early delivery.

A 1995 study by the California Department of Health Services found that the risk of miscarriage was increased two to three fold for certain women who reported high levels of job stress.

James McCubbin, PhD, and other researchers at the University of Kentucky College of Medicine, measured pregnant women’s blood pressure following a stressful arithmetic task.

The researchers speculate that increased levels of stress related hormones may affect both maternal blood pressure and fetal growth and development. While this study is preliminary, it may lead to a new approach to identifying a group of women who are at risk of pre-term labour and of having a low birth weight baby, and who may possibly be able to reduce their risk by practicing stress-reduction techniques.