Multiple mediation analysis of a task-shared psychosocial intervention for perinatal anxiety: Exploratory findings from a randomized controlled trial in Pakistan.

Background: The "Healthy Mother Healthy Baby" (HMHB) study is a phase three, single-blind randomized clinical trial conducted at Holy Family Hospital (HFH) in association with Rawalpindi Medical University (RMU). We aimed to examine the mediators of a specialized psychosocial approach based on Cognitive Behavioural Therapy principles, targeting pregnant women experiencing anxiety. The HMHB intervention was effective in treating perinatal anxiety symptoms and preventing future depressive episodes.

Methods: The trial randomized participants into two arms: the HMHB intervention or Enhanced Usual Care (EUC), following World Health Organization guidelines. The HMHB intervention comprised strategies to strengthen social support networks, improving mother-baby bonding and strategies to deal with interpersonal conflicts, economic challenges, and societal gender preferences using cognitive and behavioural techniques and culturally resonant illustrations. Participants underwent rigorous data collection at three pivotal timepoints: baseline, third trimester, and 6-weeks postnatal. The primary outcome was anxiety symptom severity scores using the Hospital Anxiety and Depression Scale (HADS) at 6-weeks post-childbirth. Four potential mediators - social support, behavioural activation, perceived stress, and pregnancy experience - were assessed in the third trimester of pregnancy.

Results: A total of 1200 participants were randomized to the HMHB and EUC arms. In the six-week follow-up time point, 379 participants remained in the EUC group, and 387 continued in the HMHB group. Post-intervention, HMHB participants displayed significant improvements in postnatal anxiety and depression scores. Mediation analyses revealed social support and pregnancy hassles as significant mediators of the intervention's effect on postnatal anxiety outcomes, while only social support emerged as a significant mediator for depression outcomes.

Conclusion: The HMHB intervention showed promising results in improving anxiety and depression scores among pregnant women. Significant mediation effects suggest the importance of targeting social support and managing pregnancy-related hassles for optimal intervention effectiveness.