Explicit and implicit caregiving interests in expectant fathers: Do endogenous and exogenous oxytocin and vasopressin matter?

• Basal neuropeptides levels in expectant fathers are not different from control men.
• Basal neuropeptides levels are unrelated to caregiving interest in expectant fathers.
• Administered vasopressin enhances expectant fathers’ implicit interest in infants.
• Expectant fathers appear to adjust for fatherhood both consciously and unconsciously.
• Vasopressin may have a more prominent role than oxytocin in upcoming fatherhood.

Caregiving interest in men (N = 46) during the third trimester of their partner's pregnancy was examined. The study included both explicit and implicit measures of caregiving interest, assessments of basal urinary concentrations of oxytocin and vasopressin, and exogenous (intranasal) application of these hormones. Compared to control men (N = 20), fathers-to-be reported more interest in direct care for children. In an immersive virtual environment, fathers-to-be, in comparison to control men, stood closer to and tended to spend more time looking at the baby-related avatars, and stood further away and tended to spend less time looking at non-baby-related avatars. Basal oxytocin and vasopressin were not related to caregiving interest in fathers-to-be, and were not different from control men. When vasopressin was administered, fathers-to-be invested more time watching the baby-related avatars compared to control men. No effects were found of exogenous oxytocin on the behavior of fathers-to-be and control men in the immersive virtual environment. These results point in the direction of an adjustment of fathers-to-be for fatherhood, both consciously and unconsciously, and support the possible role of vasopressin in human behavior in the transition to fatherhood.