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.
What exactly is pCRH? During non-pregnant times, it is produced in the brain and influences levels of other stress hormones like cortisol. But during pregnancy, the placenta generates about 100 times that which the brain normally does. Yim says the hormone is often dubbed the "pregnancy clock", because it's thought to help ready a woman's body for the stresses of childbirth. After giving birth, however, the hormone levels drop, and causing a "withdrawal"-like effect, Yim says, "It puts the whole system out of whack."
It makes sense, then, that those women with the highest pCRH levels during pregnancy would have the greatest "withdrawal" effect, and experience postpartum depression more often, and perhaps more severely, than others.
Yim and her colleagues suggest that a simple blood screen for high pCRH levels, taken in tandem with the routine diabetes blood test that is usually done between weeks 24 and 28, might be a highly beneficial — and easy — way to screen women for postpartum depression.
As an alternative to medications for depression, Yim is a proponent of the preventative approach, suggesting that prenatal yoga classes and working to strengthen the personal connections that women may need after giving birth can be effective avenues to take.