An article in yesterday’s New York Times claims that becoming a father reduces a man’s testosterone levels.  Is it true, and should dads be concerned?

Yes, and in most cases, no.

It’s been known for a long time that both long-term relationships and fatherhood are associated with lower testosterone (T) in human males, but the study cited by the New York Times is the first to show that the relationship is causal; becoming a father actually lowers T levels.  Furthermore, the more active and involved the dad (playing, cuddling, changing diapers, etc.), the greater the drop in T.

This sounds bad.  Most dads don’t want to trade off manliness for fatherhood.  Is that what the study implicates?