Women who have higher levels of a hormone produced by the placenta midway through their pregnancy appear more likely to develop postpartum depression, according to a report in the February issue of Archives of General Psychiatry.
Postpartum depression (PPD) is more serious than "baby blues" and begins within four to six weeks of giving birth, according to background information in the article. Risk factors include a history of depression, stressful life events, a lack of social support, low self-esteem and depression, anxiety or stress during pregnancy. However, these risk factors explain only a portion of the differences between women who develop PPD and those who do not.
"Endocrine risk factors for PPD have been identified as well, including changes in reproductive hormones during pregnancy, a history of premenstrual syndrome and a history of oral contraceptive–induced mood changes," the authors write. A possible link between a hormone produced by the placenta, known as placental corticotropin-releasing hormone (pCRH), and PPD has also been hypothesized. Ilona S. Yim, Ph.D., of the University of California, Irvine, and colleagues studied this hormone in 100 pregnant women who visited two southern California medical centers during the study period. Blood samples were taken at 15, 19, 25, 31 and 37 weeks' gestational age, and symptoms of depression were assessed at the last four pregnancy visits and again an average of 8.7 weeks after delivery.
A total of 16 women developed PPD symptoms at the follow-up visit. Levels of pCRH when the women were 25 weeks pregnant strongly predicted the development of PPD. A cutoff of 56.86 picograms of pCRH per milliliter of blood has a sensitivity of 0.75 and a specificity of 0.74 for PPD, meaning that about three-fourths of women with future PPD would be identified using this marker and only 24 percent of women would be misclassified. The predictive capability of the hormone levels increased when midpregnancy depressive symptoms were also assessed.