Fatherhood reduces testosterone

It is an interesting incidence of nature that at the time a man needs the least amount of testosterone, his body accommodates him. Shortly after the birth of a child, when a baby becomes part of the home, a man's testosterone level drops measurably making him more able to focus on caring for the baby.

The reduction also lowers his fertility and sex drive at a time when having another baby would not be optimal.

High levels of testosterone increase sexual interest and risk-taking behaviors and raise the drive for social dominance. These are counter productive traits in the presence of a newborn baby.

"Our study shows that human fathers are biologically wired to help with the job," said Christopher Kuzawa, from Northwestern University who worked on the study published in the Proceedings of the National Academy of Sciences.

Other studies have recognized that fathers had a lower testosterone level than non-fathers. But the question always existed about the relationship of testosterone to fatherhood. Did men with lower hormone levels just become fathers more easily than men with higher levels? Or was it the event of fatherhood that lowered the hormone?

Now we know it's the event. The followed a group of 600 men for over five years, measuring their testosterone along the way. Data shows that after fatherhood, the hormone levels decrease for a short time and increase back to normal levels.

"Fatherhood and the demands of having a newborn baby require many emotional, psychological and physical adjustments," said Lee Gettler also of Northwestern University. "Our study indicates that a man's biology can change substantially to help meet those demands."

Source: Reuters