Longitudinal evidence that fatherhood decreases testosterone in human males

TLDR

In many species, testosterone rises during mating but falls to facilitate caregiving, and while this pattern may apply to humans, prior cross‑sectional studies have left unclear whether fatherhood suppresses testosterone or whether lower testosterone predisposes men to fatherhood. The study aimed to determine whether baseline testosterone predicts later fatherhood and whether testosterone levels change after becoming a father. Using a large representative sample of 624 Filipino men, the authors followed single non‑fathers over 4.5 years, measuring waking testosterone at baseline and at follow‑up to assess changes associated with partnership and fatherhood. High baseline waking testosterone increased the likelihood of becoming a partnered father, and fathers subsequently experienced marked declines in waking (−26 %) and evening (−34 %) testosterone, especially those spending ≥3 h daily childcare, demonstrating a bidirectional relationship where testosterone predicts mating success but is suppressed by parenting, potentially explaining health disparities between fathers and single men.

Abstract

In species in which males care for young, testosterone (T) is often high during mating periods but then declines to allow for caregiving of resulting offspring. This model may apply to human males, but past human studies of T and fatherhood have been cross-sectional, making it unclear whether fatherhood suppresses T or if men with lower T are more likely to become fathers. Here, we use a large representative study in the Philippines ( n = 624) to show that among single nonfathers at baseline (2005) (21.5 ± 0.3 y), men with high waking T were more likely to become partnered fathers by the time of follow-up 4.5 y later ( P < 0.05). Men who became partnered fathers then experienced large declines in waking (median: −26%) and evening (median: −34%) T, which were significantly greater than declines in single nonfathers ( P < 0.001). Consistent with the hypothesis that child interaction suppresses T, fathers reporting 3 h or more of daily childcare had lower T at follow-up compared with fathers not involved in care ( P < 0.05). Using longitudinal data, these findings show that T and reproductive strategy have bidirectional relationships in human males, with high T predicting subsequent mating success but then declining rapidly after men become fathers. Our findings suggest that T mediates tradeoffs between mating and parenting in humans, as seen in other species in which fathers care for young. They also highlight one likely explanation for previously observed health disparities between partnered fathers and single men.