Men and women both produce testosterone (male hormone) and estrogen (female hormone), as well as prolactin (the hormone that stimulates milk production by breast tissue).

The difference between the sexes in this regard is only a matter of the relative concentrations (ratios) of these hormones.

Changes occur in concentrations of these hormones in the blood of pregnant women that prepare them for motherhood. Canadian researchers have found that similar changes occur in men during their wives’ pregnancies...

These changes can be most conveniently followed, the Canadian researchers found, by measuring hormonal concentrations in saliva, which mirror their concentrations in the blood.

Starting early in pregnancy and continuing for 3 months after the pregnancy was completed, they collected saliva every week from 45 men who accompanied their wives to a prenatal clinic.

Surprisingly, hormone levels of the men became more like those of women during the last 3 weeks of their wives’ pregnancies, and continued so during the postnatal period. 

Thus, the men’s testosterone levels sank, while their estrogen and prolactin levels rose. Their cortisone levels also rose during the week prior to birth, probably helping them to cope more easily with the stress.

These changes possibly prepare men mentally for fatherhood and, it is thought, may help them to assist with child rearing and domestic affairs. [Mayo Clinic Proceedings 76:582, 2001; Global Family Life News, 10/02]