Predicting infant–father attachment: the role of pre- and postnatal triadic family alliance and paternal testosterone levels

This longitudinal study examined whether prenatal family alliance and prenatal paternal testosterone levels predicted infant–mother and infant–father attachment security and whether this association was mediated by postnatal family alliance and postnatal paternal testosterone levels. In 105 couples expecting their first child, family alliance was assessed in the third trimester of pregnancy with the prenatal version of the Lausanne Trilogue Play (LTP). Family alliance was measured again 6 months postnatally, using the LTP. Fathers provided testosterone samples prenatally and at 6 months postnatally. Infant–parent attachment was assessed with the Attachment Q-Sort (AQS) at 24 months. Results indicated an increase in paternal testosterone levels from the pre- to the postnatal period. A more positive prenatal family alliance predicted higher infant–father attachment security at 24 months, but not infant–mother attachment security. The association between prenatal family alliance and attachment security was not mediated by postnatal family alliance or postnatal paternal testosterone levels. This study highlights the significance of prenatal family relations, and the need to consider in research and practice the divergent effects of prenatal family alliance patterns on the emerging infant–mother and infant–father attachment relationships. The underlying hormonal mechanisms during the transition to fatherhood are important targets for future research.