Part of the BBC series ” The Biology of Dads” looks into the phenomenon of expecting dads who experience pregnancy symptoms. You may have heard about this, it’s known as “sympathetic pregnancy” or “couvade” (hatching) syndrome and there’s research showing that men can get queasy, experience cravings, weight gain, aversions, and exhaustion in a similar pattern to their pregnant partners. It’s been speculated that this is a psychological or psychosomatic response, but it seems there’s a hormonal basis.
Expecting dads can temporarily produce higher levels of the “mothering” or breastfeeding hormone PROLACTIN. In one study, 55% of expecting dads showed increased prolactin. When the producers of the BBC series measured the prolactin level in a brand new father as he held his baby, it was up by 20%.
Prolactin is released in pregnancy to help develop breast tissue and then peaks when a woman is lactating. (Some ambitious men are able to lactate if they are given high doses of prolactin.) But prolactin is not unique to motherhood; it’s present in all humans and is associated with sleep. I know that for breastfeeding women it’s associated with being very relaxed or out-of-it.
Also, of significance: the higher the prolactin, the lower the testosterone.
As Laverne Antrobus puts it in The Daily Mail: “Now, we know there is a physiological reason for the phenomenon of the ‘big softy’.” Lower testosterone is also associated with a decreased sex drive.
In other words, good-bye morning wood, hello morning sickness.