In a surprising report
that goes against expectations, researchers at Northwestern University found that higher levels of the hormone oxytocin is correlated with increased risks for postpartum depression. But does this really make sense?
The results surprised even the researchers who conducted the study, as they expected postpartum depression to be associated with lower oxytocin levels.
Oxytocin is a hormone released by the pituitary gland in the brain. It’s often referred to as the “cuddle hormone” or the “love hormone” as the chemical is released during times of social bonding. In women, the hormone is especially important in labor and delivery. During nursing, suckling of the breast by a baby stimulates the flood of oxytocin to the woman’s body, which then causes her body to produce more milk for the baby. These processes, regulated by oxytocin, increase mother-child bonding and should promote wellness postpartum.
In a cohort of 66 healthy pregnant women, researchers identified 13 in the group that had a history of major depressive disorder and 53 that did not. They measured the oxytocin levels in these women at the third trimester and signs of depressive symptoms at 6 weeks postpartum. The researchers noted no differences between the two groups in terms of demographic factors or birth outcomes.
The research team reported that higher oxytocin levels predicted greater postpartum depression symptoms in women with a past history of depression only. In other words, the results say that women who experienced prior depression and have high oxytocin levels at the third trimester are more likely to experience postpartum depression.
But there’s much room for skepticism in these results, especially given the knowledge of how oxytocin acts to promote mother-child bonding and stress management. Dubiously, the strange correlation only holds up for women with a past history of depression. To address this obvious question, Suena Massey, first study author, said, “There's emerging research that a past history of depression can change the oxytocin receptor in such a way that it becomes less efficient. Perhaps, when women are starting to experience early signs of depression, their bodies release more oxytocin to combat it."
Perhaps this could be a new adaptive mechanism in postpartum depression. But with such a small sample size, these speculations are far from convincing.
To be more conclusive, the researchers would need to significantly increase the sample size, and they would also need to make more stringent comparisons. For example, are there differences in oxytocin levels in women with a past history of depression that did not experience postpartum depression? And what about women who develop postpartum depression but had no prior history?
The study authors acknowledge these limitations, but propose that oxytocin could be a predictor in postpartum depression. “It's not ready to become a new blood test yet," Massey acknowledged. "But it tells us that we are on the track to identifying biomarkers to help predict postpartum depression."
Additional source: EurekAlert!