Postpartum depression in women is starting to get the medical and societal attention it deserves, but postpartum depression in men is still little understood. While paternal postpartum depression has been documented in 7 to 10% of new fathers, some mental health professionals question its equation with the complex hormonal fluctuation women experience after giving birth. But a growing body of research suggests hormonal changes may be behind a new dad’s depression, too.

The study, published in the journal Hormones and Behavior, followed 149 couples during the first two years after the birth of a first, second or third child. Interviewers checked in at 2 months post-birth, 9 months, and 15 months. At the 9-month visit, researchers gave the fathers saliva sample kits. Dads took samples three times a day — morning, midday and evening — to monitor their levels of testosterone, a hormone associated with aggression and parental care. Participants responded to questions about postpartum depression symptoms based on the widely-used Edinburgh Postnatal Depression screening tool. They also reported on their relationship satisfaction, parenting stress and whether they were experiencing any intimate partner aggression.

Researchers, led by Darby Saxbe, PhD, a professor of psychology at the University of Southern California, then linked the men’s testosterone levels to their own and their partners’ symptoms of postnatal depression — and found opposing correlations. Higher testosterone levels correlated to less risk of postpartum depression in men, but increased their female partners’ symptoms of postpartum depression. Whereas, lower testosterone was associated with more postpartum depression symptoms in men, but fewer symptoms in their female partners. (This link was mediated, however, by relationship satisfaction; if paired with lower-testosterone partners, women reported greater satisfaction with their relationship, which in turn helped reduce their depressive symptoms.)

“It may be that the fathers with lower testosterone were spending more time caring for the baby or that they had hormone profiles that were more synced up with mothers,” Saxby said. “For mothers, we know that social support buffers the risk of postpartum depression.”

Fathers with higher testosterone levels reported more parenting stress, and their partners reported more relationship aggression.

Parents were also asked how strongly they related to a set of 36 statements designed to measure parenting stress, such as “I feel trapped by my responsibilities as a parent” and “My child makes more demands on me than most children.” Relationship satisfaction questions were based on another accepted scale that measures 32 points of relationship satisfaction, including areas of disagreement or their degree of closeness and affection. Higher scores signaled greater dissatisfaction.

Mothers also answered questions from another scientific questionnaire, the HITS (Hurts, Insults, and Threats Scale), reporting whether they had experienced any physical hurt, insult, threats and screaming over the past year. They also were asked if their partners restricted activities such as spending money, visiting family or friends or going places that they needed to go.

“Those are risk factors that can contribute to depression over the long term,” Saxbe said.

Saxbe cautioned, however, that testosterone supplementation is not the way to treat postpartum depression in men.

“One take-away from this study is that supplementing is not a good idea for treating fathers with postpartum depression,” she said. “Low testosterone during the postpartum period may be a normal and natural adaptation to parenthood.”

Indeed, earlier research suggests impending fatherhood lowers men’s levels of testosterone and estradiol, a hormone associated with caregiving and bonding, during the prenatal period. Conversely, women in the same study showed large prenatal increases in both hormones, as well as in cortisol (a stress hormone) and progesterone (associated with social closeness and maternal behavior). It’s possible that both sexes’ physiological changes set the stage for some kind of postpartum baby blues.

But how — and if — these blues manifest in men and women is, perhaps, the sticking point for some experts. Per The New York Times:

Dr. Jennifer L. Payne, director of the Women’s Mood Disorders Center at Johns Hopkins School of Medicine, said the new research helps shed light on the role that spouses and hormones may play in the condition but stopped short of labeling what men experience as postpartum depression. The U.S.C. study, she said, “was about depressive symptoms, and I would not call that postpartum depression. I think that’s a very different ballgame.”

For some, however, that’s mere quibbling.

“To a certain extent, any postpartum depression is just depression that happens to emerge in the postpartum period,” Saxbe told the Times. “It’s not super conclusive that there’s an obvious hormonal reason in women, either.”