Postpartum factors related to mother's recognition of newborn infant odours

Testosterone and prolactin are associated with emotional responses to infant cries in new fathers

To determine the responsiveness of new fathers and non-fathers toward infant cues, we exposed fathers and non-fathers to infant cries and to control stimuli and we measured affective, heart-rate, and endocrine responses, including salivary testosterone and cortisol and plasma prolactin concentrations prior to and after cry presentations. We found that (1) fathers hearing the cry stimuli felt more sympathetic and more alert compared to groups who did not hear the cries or to non-fathers who heard the cries; (2) fathers and non-fathers with lower testosterone levels had higher sympathy and/or need to respond to the infant cries than fathers with higher testosterone levels; (3) fathers with higher, as opposed to lower, prolactin levels were also more alert and more positive in response to the cries; (4) fathers hearing the cry stimuli showed greater percentage increase in testosterone than fathers not hearing the cry stimuli; (5) experienced fathers hearing the cries showed a greater percentage increase in prolactin levels compared to first-time fathers or to any group of fathers hearing control stimuli; finally, (6) partial correlations with parity and experience entered as a covariates indicated that both experience and testosterone contributed to the variance in fathers' affective responses to infant cries. Taken together, these results indicate that, as with a number of other biparental species, human fathers are more responsive to infant cues than are non-fathers and fathers' responses to infant cues are related to both hormones and to caregiving experience.