Curious Parents

Dads-to-Be Experience Hormonal Changes, Too

Becoming pregnant completely transforms a woman's body. Hormonal changes alter everything from her hunger levels to the flexibility of her joints. But she's not the only one that transforms: A growing body of research is showing that expectant fathers go through hormonal changes of their own.

This Is Your Brain on Babies

For years, research has shown that men experience hormonal changes after the birth of a baby. Several studies find that fathers interacting with their new bundle of joy is associated with an increase in oxytocin, the so-called "love" or "cuddle" hormone. Other studies have found that men who stay close to their kiddos experience a rise in vasopressin, the "bonding" hormone, and prolactin, the hormone that keeps your eyes from wandering toward new potential mates. With the rise in these nurturing hormones comes a drop in testosterone, the infamous male hormone that's associated with aggression, risk-taking, and high libido.

There's been one caveat with all of this research, however. Dad has to be near his kids to experience the hormonal effects. "There seems to be some kind of fundamental social-neurobiological framework that comes into play when fathers interact with their kids," researcher Lee Gettler told NBC. But more recent research suggests otherwise.

What to Expect When You're Expecting

A 2014 study published in the American Journal of Human Biology says that hormonal changes happen in fathers even before their baby is born. Dr. Robin Edelstein of the University of Michigan and her team tested the saliva of 29 couples who were expecting a first baby. They administered the tests at 12, 20, 28, and 36 weeks, respectively. As expected, all four of the hormones they were studying increased in women, including testosterone, cortisol (the stress hormone), estradiol (a form of estrogen associated with caregiving and bonding), and progesterone (a female hormone associated with maternal behavior). But perhaps surprising is what happened in men: Their cortisol and progesterone levels stayed the same, but their estradiol and testosterone levels decreased. The changes began as early as 20 weeks. This seems to show that biology prepares both parents for the challenges of raising a child.

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Learn more about the science of parenthood in "Our Babies, Ourselves: Why We Raise Our Children the Way We Do" by Meredith F. Small. We handpick reading recommendations we think you may like. If you choose to make a purchase, Curiosity will get a share of the sale.

Written by Ashley Hamer February 1, 2017

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