A stressful interaction with a young child can result in short-term changes in both mothers’ and fathers’ testosterone levels, according to new research published in the journal Hormones and Behavior. The findings provide more evidence that reductions in testosterone are linked to parental tendencies such as nurturance and empathy.

“There’s some evidence linking lower testosterone (T) with more involved parenting and more nurturant caregiving, so we had reasons to expect that interactions with children might lower parents’ T,” said study author Robin Edelstein, an associate professor of psychology at the University of Michigan.

“But most of the work in this area is correlational (e.g., people with lower T report being more involved in childcare); not many studies have looked at short-term changes in T experimentally or as a function of actual parenting interactions. And the work that does exist is primarily focused on women, so we were interested in looking at whether we would see changes in both mothers’ and fathers’ T.”

In the study, 146 mothers and 154 fathers engaged in a moderately stressful task with their one-year old infants. The stressful task is known as the strange situation procedure, in which infants go through a series of separations and subsequent reunions with a parent — often leading the child to become upset and require nurturance from a mother or father.

For testosterone measurements, the participants provided saliva samples when they first arrived at the laboratory and again after the strange situation procedure.

“Both mothers and fathers showed decreases in T after interacting with their child during a stressful task. This lends support to the idea that nurturant interactions can lead to short-term declines in T. Because so few studies on this topic include women, this is some of the first evidence for short-term T declines in women in caregiving contexts,” Edelstein told PsyPost.

The researchers also found that fathers with a more avoidant attachment orientation tended to have smaller declines in testosterone.

“Fathers who reported more discomfort with closeness were less likely to show these effects, suggesting that not everyone shows T declines to the same extent and that individual differences in people’s approaches to close relationships may be important predictors of T changes,” Edelstein explained.

“We measured comfort with closeness in the context of romantic relationships, so it’s especially interesting that this individual difference predicted fathers’ T responses to interactions with their infants. This finding lends support to the idea that people’s’ feelings and beliefs about relationships may apply to their relationships more generally as opposed to one kind of relationship specifically.”

But the study — like all research — includes some limitations.

“We didn’t find that mothers’ comfort with closeness predicted their T responses. So although women on average showed T declines, individual differences in these declines may be related to some other characteristics for mothers. This is a question that will need to be addressed in future research,” Edelstein said.

“One important caveat is that we did not compare parents’ responses to any sort of ‘control task’ (like a less stressful play session). So although we believe that the changes we saw were due to parents providing nurturance to their distressed infant, we cannot be entirely sure. Future research might also include multiple tasks to see whether and how hormones change in different contexts.”

The study, “Adult attachment and testosterone reactivity: Fathers’ avoidance predicts changes in testosterone during the strange situation procedure“, was authored by Robin S. Edelstein, Kristi Chin, Ekjyot K. Saini, Patty X. Kuo, Oliver C. Schultheiss, and Brenda L. Volling.