Spillover effects on the relationship with the partner of a mentalization-based intervention for pregnant women.

The birth of a child has been associated with a decline in couple satisfaction, which has implications for the child's social-emotional development. This study investigated the potential spillover effect on pregnant women's perceptions of their relationships with their partners of the Supporting the Transition to and Engagement in Parenthood (STEP) program, a brief trauma-informed mentalization-based prenatal group intervention. Participants (94% White) were recruited in prenatal clinics and through online advertisements in Quebec, Canada. Both quantitative and qualitative data were collected from participants assigned to the STEP program (n = 42) and those receiving treatment-as-usual (TAU; n = 125). Women participating in STEP reported significant improvements in their relationships with their partners compared to those assigned to TAU. More precisely, they reported higher couple satisfaction, enhanced communication, and increased interest in their partners' emotional experience. The qualitative analysis further substantiated these results, with participants reporting having involved their partners in their pregnancy, shared their insights about themselves with their partners and gained fresh perspectives on their relationships. Participants in STEP also expressed sharing program materials with their partners and considered that such interventions should be extended to expecting fathers. This study underscores the potential of mentalization-based interventions to indirectly contribute to couple relationships, which may have positive implications for parenting and the infant.