Ilona S. Yim and her team at the University of California, Irvine took blood samples from 100 pregnant women at weeks 15, 19, 25, 31, and 37 of pregnancy. The blood was analyzed for levels of three stress hormones: pCRH, cortisol, and adrenocorticotropic hormone (ACTH). Separately, the women were checked for depression symptoms during the last four visits while pregnant, and then again nine weeks after giving birth. Yim and her colleagues found that high levels of pCRH at week 25 were strongly correlated with depression symptoms after giving birth, and correctly predicted about 75% of the postpartum depression cases observed.
During non-pregnant times, pCRH is produced in the brain and influences levels of other stress hormones like cortisol.