The intensive demands of parenting require huge adjustments from both parents. However, the study, Cebu Longitudinal Health and Nutrition Survey, suggests that men undergo extra adjustment to cope better with child rearing. Encompassing three generations of participants in Cebu from the 1980’s up to the present, the survey collected data on various aspects of human health and nutrition including, reproductive health and sexuality.

During the presentation of the results of the study at the Department of Health (DOH) 13th National Health Forum for Action, Dr. Nanette Lee-Mayol, Research Associate at the University of San Carlos (USC) - Cebu City, shared that the level of testosterone in men is affected by courtship, marriage and subsequent fatherhood.

Researchers measured morning and evening salivary testosterone level of the 624 single, adult male participants. Baseline data were first collected in 2005. The test was repeated after four years in 2009 when some of the participants were already married. Study showed that levels of morning and evening salivary testosterone of men who became fathers declined by 26% and 34%, respectively, whereas single non-fathers only experienced a decrease of 12% and 14% in their respective morning and evening testosterone level. Researchers also discovered that the men who spend most time with their kids are likelier to get lower testosterone levels than the others. These fathers whose youngest child was less than a month old experienced the most drastic decline in testosterone levels. Dr. Mayol revealed, “The more involved you are in taking care of the children, especially the very young ones, the lower your testosterone.”

Though there were researches made on primates showing similar results, no other paper has been published yet that links child rearing with decline in testosterone in human males until the Cebu longitudinal study. The study was the first to conclusively connect child rearing to lowered testosterone levels in men.

While traditionally, child rearing has always been designated solely as a woman’s responsibility, the study proves otherwise. The researchers explained that while high testosterone ensures mating success in men, the steep decline in testosterone level showed that men are innately wired to actively help in the child rearing.  Dr. Mayol stressed, “Testosterone is often high during mating periods but then declines to allow for caregiving of the resulting children.”