Fathers Today: The Role of Hormones in Father's Sensitive and Protective Parenting

Summary:

Whereas previous research has mostly focused on the hormonal, behavioral and neural correlates of maternal caregiving, the present study will examine the hormonal, behavioral, and neural dynamics of paternal behavior in first-time fathers during a specific phase of fatherhood: between 2 and 7 months after the baby has been born. The study includes a randomized, double-blind, placebo-controlled within-subject design to examine the effects of intranasal administration of oxytocin and vasopressin on parenting behavior and the neural and behavioral responses to infant signals. In addition, we will examine whether effects of oxytocin and vasopressin are moderated by fathers’ early childhood experiences.

Study population:

A total of 55 first-time fathers of a child aged between 2 and 7 months old will visit our lab for three experimental sessions. The experimental sessions include the following conditions: intranasal administration of (1) oxytocin, (2) vasopressin, and (3) a placebo. Participants will be randomly assigned to order of administration. Participants and researchers are blind to order of administration. The experimental sessions will take place with intervening periods of 1 to 2 weeks.

Intervention:

Participants are randomly assigned to one of the six counterbalanced orders of conditions. Participants are instructed to self-administer oxytocin (Syntocinon®, 24 IU/ml, registered in the Netherlands as RVG 03716), vasopressin (Vasostrict®, 20 IU/ml), or placebo (Chlorbutanol solution) using a nasal spray. Self-administration takes place under supervision of a researcher blind to condition. All experimental medication is prepared by the hospital pharmacy of the Amsterdam University Medical Centre. Randomization of administration is performed by an independent researcher who is not involved in the study. Randomization is performed before the start of the interventions using a computer-generated randomization sequence. Researchers and participants are blind to order of assignment.

Our primary hypotheses are:

1. We hypothesize that infant-father interactions in the oxytocin and vasopressin condition are characterized by enhanced stimulatory and sensitive play and increased paternal protective behavior as compared to the placebo condition.
2. We expect that oxytocin and vasopressin administration affect behavioral responses to infant cry sounds and neural responses to infant cry sounds and threat to the infant.

Participants will visit our research centrum for three experimental sessions.

Administration of oxytocin, vasopressin, and placebo. Participants are randomly assigned to one of the six counterbalanced orders of conditions.