Although men may not be aware of it, they actually undergo hormonal changes as they prepare for fatherhood, says neuropsychiatrist Louann Brizendine, author of The Male Brain (Broadway Books, $24.99), released in March.
At first, those hormones tell them to panic, or at least pay attention.
Levels of a stress hormone called cortisol — the same ancient chemical that instructs men to fight or take flight — tend to spike about four to six weeks after men learn they’re going to be fathers, subsiding as the mother’s pregnancy progresses, Brizendine says.
“It is a cortisol surge that wakes our brains up every morning,” Brizendine says. “So this surge may put the father-to-be’s brain on alert and in a sense wake him up to the impending reality of a new baby’s coming, and alert him that he’d better get things ready.”
About three weeks before the baby arrives, levels of testosterone — sometimes called the “male hormone,” associated with competitiveness, aggression and sex drive — fall by roughly a third, Brizendine says.