New York, Dec 16 (IANS): Not just mothers, even fathers go through hormonal changes as the date of delivery comes closer, finds a study.

Previous studies have shown that men's hormones change once they become fathers.

"But our findings suggest that these changes may begin even earlier, during the transition to fatherhood," said lead study author Robin Edelstein from University of Michigan.

During the study, researchers found that women showed large prenatal increases in salivary testosterone, cortisol, estradiol and progesterone levels while men showed significant prenatal declines in testosterone and estradiol but no detectable changes in cortisol or progesterone.

While the results in women were expected, the results seen in men suggest that impending fatherhood might cause men's hormone levels to change.

"We do not yet know exactly why men's hormones are changing; these changes could be a function of psychological changes that men experience as they prepare to become fathers, changes in their romantic relationships, or even physical changes that men experience along with their pregnant partners," Edelstein explained.

Additional studies are warranted to understand whether partners' prenatal hormone changes are linked with postpartum behaviour and adjustment.

The study appeared in the American Journal of Human Biology.