New publications
Fatherhood dramatically lowers testosterone levels in men
Last reviewed: 30.06.2025
All iLive content is medically reviewed or fact checked to ensure as much factual accuracy as possible.
We have strict sourcing guidelines and only link to reputable media sites, academic research institutions and, whenever possible, medically peer reviewed studies. Note that the numbers in parentheses ([1], [2], etc.) are clickable links to these studies.
If you feel that any of our content is inaccurate, out-of-date, or otherwise questionable, please select it and press Ctrl + Enter.
Humans seem to be the only creatures on Earth that raise their young for twenty years or more. This is such a shock to men that they seem to have developed a biological mechanism to cope with the need to expend energy on offspring.
A new study has found that men experience a sharp drop in testosterone levels after becoming a father, suggesting that aggression and competitiveness are less useful when it comes to raising children.
Previous studies have shown that young fathers have lower testosterone levels than men of the same age who don't have children. But no study has yet been able to answer the question: does having a child cause testosterone levels to drop, or do men with low levels of the hormone make devoted husbands and caring fathers?
To get to the bottom of this, anthropologists Lee Gettler, Christopher Kuzawa, and colleagues at Northwestern University and the University of San Carlos in the Philippines tested testosterone levels in men participating in a longitudinal study of residents of Cebu, Philippines. It began in 1983 with 3,000 women who were pregnant at the time, and then followed the general health, nutrition, and medical care of their children, who now have children of their own, so the project spanned more than one generation.
In short, a large group of men has been studied for almost thirty years - since birth, which is unprecedented. In 2005, scientists measured the morning and evening testosterone levels in the saliva of about six hundred men and repeated the analysis in 2009.
It turned out that men with high testosterone levels were more likely to become devoted partners and fathers, after which there was a sharp drop in hormone levels compared to their childless peers - by 26% in the morning and by 34% in the evening, while for "non-dads" the age-related decline rates were 12% and 14%, respectively.
The study also found that testosterone levels were lowest among those who spent the most time caring for children. Low levels of the hormone also correlated with the age of the children, with the steepest drop recorded among fathers of newborns.
"The decline in testosterone appears to be a normal biological adjustment that helps men rethink their priorities when they have children," Mr. Kuzawa says. Other studies, by the way, have found that men with high testosterone levels are more likely to have marital problems and divorce. In one study, such men felt less empathy and less need to respond to a baby's cries.
This challenges the classic hypothesis that men evolved solely to be food providers. As we see, fathers are biologically predisposed to care for children. In other words, fatherhood is a normal aspect of masculinity.
[