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Placental hormone surge at the end of pregnancy is linked to postpartum depression
Last reviewed: 02.07.2025
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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 findings, published in the journal 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 at risk.
"One in five women reports elevated depressive symptoms in the year after giving birth," said lead author Isabel F. Almeida, associate professor of Chicano/Latino studies and director of the Latina Perinatal Health Lab at UC Irvine.
"Symptoms of depression after childbirth can have a negative impact on mothers, children and families, so it is important to understand the causes."
Co-authors of the study include Gabrielle R. Rinn, a doctoral student in health psychology at UCLA; Christine Dunkel Schetter, a distinguished researcher and professor of psychology at UCLA; and Mary Kuzons-Reed, a 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/Latina, black, and Asian) throughout pregnancy and for one year after giving birth.
Blood samples were collected at three prenatal visits—one at 8-16 weeks of pregnancy, one at 20-26 weeks of pregnancy, and one at 30-36 weeks of pregnancy. A 10-item survey was also administered at one, six, and 12 months postpartum to track the onset and severity of depressive symptoms.
"Previous studies have focused on a single time point to assess pCRH levels, whereas our work characterized complex pCRH changes across pregnancy to clarify links with postpartum mental health," Almeida said. "This person-centered approach was key because it allowed us to identify and compare subgroups of individuals and their trajectories at a more granular level across pregnancy and postpartum."
PCRH levels have 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, particularly between mid- and late pregnancy. Specifically, the 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 postpartum, with women in the accelerated group reporting slightly higher depressive symptoms than those in the typical and flat groups.
Almeida said the findings suggest that pCRG 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, paying particular attention to patterns of changes in pCRG."