Researchers from the University of California, Irvine say that the level of a hormone produced by the placenta around the 25th week of pregnancy may help predict a woman's chance of developing postpartum depression.
Ilona S. Yim, PhD, and colleagues analyzed blood samples from 100 pregnant women and found that those who had higher levels of placental corticotropin-releasing hormone (pCRH) midway through pregnancy were more likely to develop postpartum depression. The blood test correctly identified 75% of those who had future postpartum depression symptoms.
The findings, published in the February issue of Archives of General Psychiatry, raise the possibility that a screening test for postpartum depression could one day become part of a woman's standard prenatal care. The researchers envision a screening test being done the same time as a gestational diabetes screen, which is typically performed around 24 to 28 weeks of pregnancy.
Postpartum depression can cause feelings of sadness and hopelessness that usually begin within the first four weeks after giving birth. It is different and more severe than the "baby blues," and symptoms last longer.
What makes a woman more likely to develop the condition is not entirely clear. Risk factors for postpartum depression include a history of depression or premenstrual syndrome, stress and anxiety during pregnancy, a lack of social support, and fluctuating hormone levels.
Some research has suggested a link between pCRH and postpartum depression, but direct evidence from observations have been lacking.
Hormone Levels and Postpartum Depression
To investigate the link between pCRH and postpartum depression, Yim's team took blood samples from each study participant at week 15, 19, 25, 31, and 37 of pregnancy and measured the levels of pCRH as well as cortisol, a stress hormone, and adrenocorticotropic hormone (ACTH), which triggers the release of cortisol.
Sixteen women developed postpartum depression symptoms by their follow-up visit. Increased pCRH at week 25 of pregnancy was the strongest predictor of development of postpartum depression and correctly identified most women at risk.
"Placental CRH in this study was a moderately sensitive and specific marker for PPD [postpartum depression] symptoms that allows for the correct identification of 75% of women with future PPD symptoms, and at the same time was characterized by a low misclassification rate (24%)," the researchers write in the journal article.
Cortisol and ACTH levels did not appear to have a significant link to the development of postpartum depression. However, some evidence suggests the surge in pCRH during mid-pregnancy may be associated with an increase in cortisol early in pregnancy.