It’s not news that new dads are often found to have elevated prolactin levels when their babies are born, but a new study from New Zealand suggests that a dad’s prolactin may influence a father’s caregiving and bonding motivations.
Researchers have found through the years that dads tend to have rising prolactin levels when their children were born, but there’s never been anything relatively conclusive on what that prolactin did in a new dad. In pregnant women and new mothers, prolactin levels are usually high and what causes breasts to grow and make milk while they’re pregnant and after they’ve given birth.
A research team from the University of Otago in New Zealand found that just as prolactin in a mother helps her bond and attach to her baby, elevated levels in a new dad may do the same. The research was published in the journal Cell, and was a two-year study that looked at how the hormone helped men bond with their children.
In general, prolactin levels are normally low for nonpregnant women and for men. But, lead author of the study Dr. KristinaSmalley and her international team found that elevated levels of prolactin in expecting fathers was a phenomenon worth studying. The Otago team paired with a team from Sweden and studied the parental behaviors of mice and rats.
They found that the male mice part in caring for their mice pups, while male rats had no part.
Dr. Smiley said that they looked at the differences in the two species of animals, and particularly how their brains produced and pumped out prolactin. Rats had really low levels of prolactin, while mice had high levels and the researchers found that correlated to their giving of parental care (or not) of their young.
When the research team switched the levels of prolactin in the mice and rats, they found different results. The mice received low levels of prolactin and made it so that their brains couldn’t respond to the prolactin, and did the opposite for the rats–upping their prolactin levels significantly.
They found that the male mice stopped taking care of their babies while the male rats started to show paternal bonding and caregiving behaviors.
Dr. Smiley said that while that occurred in mice and rats, there are definitely other hormone levels that play in when a baby is born–for the mother and the dad–and that changing the hormone levels in a father to increase paternal bonding was a lot trickier to do than it would be in mice or rats.
Dr. Smiley noted that while expecting mothers typically get prenatal care in which hormone levels are checked, as well as postpartum care (we hope) where the same occurs, the same isn’t done for fathers at all, as they’ve not been the ones giving birth.
Still, she and her team found that as prolactin rose during fatherhood, testosterone levels in men also seemed to drop, and maybe that’s a key to the interaction. She said that the findings opened up several more questions about the relationship of hormones in an expecting father and the bond and attachment he has with his new child.
Dr. Smileyalso noted that when looking at mood disorders and postpartum depression, it was important to note the differences in the two between parents and non-parents. For example, a brain scan of a postpartum depressive person will look very different than someone who suffered from major depression, yet we’re treating both of the conditions as they’re the same when they are clearly not.
She said that similar mood changes happened in fathers as well, but it’s not completely understood why. As such, we can’t make specialized treatment for men and women until we look at how parental care is regulated. When it comes to depression and postpartum depression, mood regulation doesn’t have as much of an impact as does parental care behaviors. In parents, there’s something specific that leads to mood disorders like postpartum depression, and that seems to be more of a disruption of the brain in areas that control parental behaviors as opposed to common depressive emotional centers of the brain.
The team will continue to look at how prolactin affects men and primes them for fatherhood, but in the meantime, good to know that dads wanting to care for and bond with their babies is instinctive too. Knowing this can help break the cultural norms that leave all the childcare and parental work for moms alone.