Hormone may predict postpartum depression: U.S. study

By Andrew Stern

CHICAGO (Reuters) - Spiking and sinking levels of a hormone that prepares a pregnant woman for the strain of childbirth may hold the key to why some women suffer postpartum depression, researchers said on Monday.

In a study of 100 women, researchers at the University of California, Irvine, found 12 out of 16 women who had postpartum depression also had high levels of a hormone circulating in the placenta midway through pregnancy.

Corticotropin-releasing hormone, or CRH, is normally produced in tiny amounts by the hypothalamus near the brain in response to stress.

In pregnant women, the placenta pumps out 100 times more CRH than is normally produced by the hypothalamus. The hormone has been nicknamed the "placental clock" because it is thought to prepare the woman's body for childbirth, said psychologist Ilona Yim, who worked on the study.

Levels of CRH and other hormones drop after the mother gives birth, which Yim said causes hormone "withdrawal" that can create havoc with the endocrine system.

"It puts the whole system out of whack," she said in a telephone interview.

CRH triggers a cascade of reactions in the pituitary and adrenal glands that culminates in increased output of stress hormones like cortisol.

Previous research suggested an overactive stress response plays a role in heart disease, Alzheimer's disease and autoimmune disorders. Stress hormones produced by a dysfunctional endocrine system may also trigger mental disorders like depression.