A surge in placental hormones at the end of pregnancy is associated with postpartum depression

A team of researchers led by the University of California, Irvine, has found a potential link between changes in a key pregnancy hormone—placental corticotropin-releasing hormone (pCRH)—and symptoms of postpartum depression.

The study results, published in the journal of Psychoneuroendocrinology, add to a growing body of research on physiological risk factors during pregnancy associated with adverse postpartum outcomes and may aid in the early identification of mothers those at risk.

“One in five women report increased symptoms of depression in the year after giving birth,” said lead author Isabel F. Almeida, assistant professor of Chicano/Latino studies and director Latina Perinatal Health Labs at UC Irvine.

"Symptoms of depression after childbirth can have a negative impact on mothers, children and families, so it is critical to understand the causes."

Co-authors of the study are Gabrielle R. Rinn, a doctoral student in health psychology at UCLA; Christine Dunkel Schetter, emeritus researcher and professor of psychology at UCLA; and Mary Couzons-Reed, professor of psychology and department chair at the University of Colorado at Colorado Springs.

The study followed 173 U.S. Women of varying income and education levels, as well as racial and ethnic groups (non-Hispanic white, Hispanic/Hispanic, black, and Asian) throughout pregnancy and one year postpartum.

Blood samples were taken at three prenatal visits - one at 8-16 weeks' gestation, one at 20-26 weeks' gestation and one at 30-36 weeks' gestation. A 10-item survey was also administered at one, six, and 12 months postpartum to track the occurrence and severity of depressive symptoms.

"Previous studies have focused on a single time point to assess pCRH levels, whereas our work characterized complex changes in pCRH throughout pregnancy to clarify links to postpartum mental health," Almeida said. "This person-centered approach was key as it allowed us to identify and compare subgroups of individuals and their trajectories at a more granular level throughout pregnancy and postpartum."

PCRH levels had previously been shown to increase exponentially throughout pregnancy, and the blood samples taken by the researchers were consistent with these patterns. However, there was variability in individual pCRH levels, especially between mid and late stages of pregnancy. Specifically, women were divided into three groups:

• Accelerated group with rapidly increasing pCRH levels.
• Typical group with normal pCRH levels.
• Flat group with low pCRH levels.

Across the study, 13.9% of participants reported depressive symptoms one month after giving birth, with women in the accelerated group reporting slightly higher depressive symptoms than those in the typical and flat groups.

Almeida said the results suggest that pCRH trajectories may influence postpartum depressive symptoms. "Our findings highlight the dynamic physiological changes that occur during pregnancy and explain how such changes are associated with postpartum health.

"Future studies should examine in more detail how changes in the stress response in the hypothalamic-pituitary-adrenal axis are associated with postpartum depressive symptoms, with particular attention to patterns of changes in pCRH."