For some 10 percent of new moms, those feelings of emotional distress turn more severe - into postpartum depression, according to the Mayo Clinic.
That's where Ilona Yim is hoping to change things.
Yim is an assistant professor at University of California-Irvine's department of psychology and social behavior who is studying the connection between the levels of a stress hormone circulating through the placenta during pregnancy and postpartum depression.
The premise? "It would make more sense to find out if someone is at risk for developing postpartum depression before it occurs," she says.
So she has been researching indicators of the disorder, hopeful that eventually women can be screened early and take some preventive measures if they're at risk.
Yim was part of a team of researchers who recently studied 100 women. The researchers found that 12 of the 16 who had postpartum depression also had high levels of Corticotropin-releasing hormone, or CRH, in the placenta halfway through pregnancy.
CRH is produced in the brain as a response to stress. But in pregnant women, the placenta produces it in overdrive, circulating more than 100 times the amount normally present in the brain by the time she reaches full term. Yim says it's thought to prepare pregnant women for the strain of childbirth.
After the baby is born, levels of CRH drop. That can cause a hormonal withdrawal that leads to other high-stress responses in the body.
The women Yim studied who had postpartum depression experienced the biggest change in those hormone levels. Those who had high levels of CRH 25 weeks into pregnancy were more likely to suffer from depression after the baby arrived.
The results of the study, which was funded by the National Institutes of Child Health and Development, were published in February in the Archives of General Psychiatry.
Yim didn't want to stop there. Interested in learning more, she is starting a new project to monitor hormone levels throughout pregnancy for women who have a higher likelihood of depression. Her latest study is being paid for by the National Institutes of Mental Health.
"I want to know whether stress during pregnancy is something that can drive these hormones and whether that is something that can drive intervention," she says.
Yim is looking for women who meet a specific set of criteria to participate in this latest effort:
- 18 years or older
- English speaking
- Less than 15 weeks pregnant