Dr. Darby Saxbe

What it looks like from some of the newest studies of moms is there's also a rebound effect.

So it's really like a U-shaped pattern of change.

And that's likely what we'll see in dads as well, but we're still doing the longitudinal studies to kind of look at that time course in dad's

over months and years.

Yeah, so they might feel like they're more able to focus on understanding what a new baby might be thinking or feeling.

And so they're sort of honing their ability to essentially bond with a new baby.

And that's what the research seems to be telling us, that when the brain changes more, and this is true in studies of both mothers and fathers,

there is better bonding.

So that these brain changes, which appear to be really normative in pregnant and newly postpartum women, and a little more variable and experience dependent in dads, these changes are kind of supporting the construction of a

healthy parent-child bond.

And that's probably due to that increased sensitivity and understanding of what a baby needs.

Yeah.

So actually, one of the best studies of this was done in the Philippines by Lee Gettler, who's a researcher at Notre Dame.

And he had a very large kind of population-level cohort of men who he followed from pre-parenthood, so starting in their late teens, early 20s.

And so there's been a lot of work on both human fathers and then in biparental animals like birds and

and primates and rodents, finding that testosterone does drop around a transition to fatherhood.

And Gettler's study was really clever because he had this long-term design.

So he could answer the question of, is it that lower testosterone men are selecting into fatherhood?

And so testosterone starts low and will stay low in these men, or is there something about becoming a father that changes our testosterone level?

And what he found is actually that the higher testosterone men were more likely to become fathers across the study observation time period, but they then showed lower testosterone if they were partnered and living with children.