The role of paternal hair testosterone and cortisol levels in father-child bonding across the perinatal period in first-time fathers.

Background: Previous research has linked short-term measures of the steroid hormones testosterone and cortisol to differences in parenting behavior in fathers. However, little research has focused on father-child bonding, the emotional dimension of the father-child relationship.

Objective: This study aims to investigate the associations of long-term testosterone and cortisol levels with father-child bonding during the postpartum period. In addition, we examined the change in cumulative testosterone levels during the transition to fatherhood.

Methods: As part of the prospective cohort study DREAM_HAIR, (expectant) fathers provided hair samples during their partners' pregnancy and at 8 weeks postpartum to quantify their long-term integrated testosterone and cortisol levels in the scalp-near 2 cm hair segment. Father-child bonding was assessed using the Postpartum Bonding Questionnaire at 8 weeks and 14 months postpartum.

Results: In the current sample of highly educated fathers with relatively low bonding difficulties, regression analyses, controlling for depressive symptoms, revealed no significant associations between postpartum hair testosterone, the change in hair testosterone from pregnancy to 8 weeks postpartum, and postpartum hair cortisol with father-child bonding. Further, we found no interaction between hair cortisol and testosterone or the change in hair testosterone from pregnancy to 8 weeks postpartum on father-child bonding.

Conclusion: The results indicate that long-term postpartum testosterone, its change from pregnancy to 8 weeks postpartum, and long-term postpartum cortisol are not associated with self-reported father-child bonding. Further research is needed to examine the differences of short and long-term steroids in relation to father-child bonding in heterogeneous samples. Additionally, conceptual research is necessary to examine the differences to mother-child bonding and to caregiving behavior.