It turns out that it isn't just expectant mom's who experience prenatal hormonal changes, as men who are soon to be dad's to go through them.
Researchers recently completed one of the most extensive investigations to date of prenatal hormones in first-time expectant couples, where women showed large prenatal increases in salivary testosterone, cortisol, estradiol, and progesterone, while men showed significant prenatal declines in testosterone and estradiol, but no detectable changes in cortisol or progesterone.
The results seen in men suggested that impending fatherhood might cause men's hormone levels to change.
Lead author of the study, Dr. Robin Edelstein, said that their findings suggest that these changes may begin even earlier, during the transition to fatherhood. Though they didn't know yet why exactly men's hormones were changing; the changes could be a function of psychological changes that men experience as they prepare to become fathers, changes in their romantic relationships, or even physical changes that men experience along with their pregnant partners.
The study is published in American Journal of Human Biology.