The current study is one of the first to prospectively examine longitudinal associations between observed father caregiving behaviors and child cortisol reactivity and regulation in response to emotional arousal at 7 and 24 months of child age. Observations of father and mother caregiving behaviors and child cortisol levels in response to challenges at 7 months and 24 months were collected. Analyses were based on a subsample of children from the Family Life Project who lived with both their biological mothers and fathers and for whom there was at least partial cortisol data (7 months: n=717; 24 months n= 579). At 7 months of child age the sample was 49.0% female, 25.8% African American, and 74.2% European American. At 24 months of child age the sample was 49.9% female, 24.7% African American and 75.3% European American. Analyses across assessment points were conducted simultaneously using mixed linear modeling for repeated measures data to test for differential effects of fathering across infancy and toddlerhood. Concurrent measures of father negativity were positively associated with greater increases in child cortisol levels in response to emotion challenge at 7 months (p = .01) and with higher overall levels of cortisol at 24 months (p < .001). However, there was no evidence that father caregiving during infancy independently predicted later cortisol activity during toddlerhood
