Longitudinal evidence that fatherhood decreases testosterone in human males.
Level 3 - non-randomized controlled study
Prospective longitudinal cohort study
PubMed 21911391 · doi:10.1073/pnas.1105403108
What was done
Researchers tracked a representative cohort of 624 single, nonfather men in the Philippines (mean age 21.5 ± 0.3 years at baseline in 2005) over a 4.5-year follow-up period. Salivary waking and evening testosterone levels were measured at baseline and follow-up to test whether initial testosterone levels predicted becoming a partnered father, whether becoming a father was associated with longitudinal testosterone changes compared to remaining single nonfathers, and whether daily childcare interaction related to testosterone concentrations.
What was found
Men with high waking testosterone at baseline were more likely to become partnered fathers by the 4.5-year follow-up (P < 0.05). Men who transitioned to partnered fatherhood experienced significant median declines in waking (-26%) and evening (-34%) testosterone, which were significantly greater than declines in single nonfathers (P < 0.001). Fathers reporting 3 hours or more of daily childcare had significantly lower testosterone at follow-up than uninvolved fathers (P < 0.05).
Why it matters
These longitudinal findings help resolve whether lower testosterone in fathers is a cause or consequence of fatherhood, demonstrating that high testosterone predicts mating success but subsequently declines with parenting and active caregiving, consistent with evolutionary trade-offs between mating and parental investment.
Limits
The study was conducted in a single population of young men in the Philippines, which may limit generalizability across different cultures, older ages, or diverse socioeconomic settings. Absolute testosterone concentrations, effect estimates with confidence intervals, and confounding variables like sleep or health changes were not reported in the abstract, and childcare duration was self-reported.
Cited by
- supports In longitudinal research in the Philippines, fathers who spent more time providing hands-on care and co-sleeping with infants showed steeper drops in testosterone.
- supports Hands-on fathers typically show approximately a 25% drop in testosterone levels.