Oxytocin and the development of parenting in humans.

A prospective longitudinal study was conducted to investigate the role of the nonapeptide oxytocin (OT) in the development of human parenting, with a particular focus on its involvement in the transition to fatherhood—a topic that has received limited attention compared to its well-documented role in parent-infant bonding in animal models. The study included 160 cohabitating mothers and fathers along with their firstborn infants, and participants were visited at their homes during the initial postpartum weeks and again when the infants reached 6 months of age. At each visit, plasma OT levels for both mothers and fathers were measured using enzyme-linked immunosorbent assay methodology, while interactions between each parent and their infant were observed and meticulously microcoded to assess specific parenting behaviors. The findings revealed that, overall, parental OT levels increased across the study period, and there were no notable differences between maternal and paternal OT concentrations at either time point; additionally, OT exhibited high intraindividual stability over the first 6 months of parenting, and the OT levels of husbands and wives were found to be interrelated at both assessments. For mothers, higher OT levels were linked to increased displays of affectionate parenting behaviors, such as the use of “motherese” vocalizations, expressions of positive affect, and instances of affectionate touch, whereas for fathers, elevated OT levels corresponded with a greater degree of stimulatory parenting behaviors, including proprioceptive contact, tactile stimulation, and the presentation of objects to the infant. These results represent the first detailed description of plasma OT levels in new fathers and mothers across the transition to parenthood, highlighting how these levels relate to typical maternal and paternal parenting behaviors, and potentially establishing a normative basis for future research into parenting under conditions of high risk.