Modifiers of effectiveness and deterioration, and prognostic factors of adherence in internet-based interventions for treatment of perinatal depression: A systematic review and individual participant data meta-analysis

Background Internet-based interventions for perinatal depression reduce depressive symptoms in new and expectant mothers. However, modifiers of their effects, and prognostic factors of adherence, are unknown. Objective To assess modifiers of effectiveness and deterioration, and prognostic factors of adherence in internet-based interventions for perinatal depression. Methods Systematic searches were conducted in three bibliographic databases on February 7, 2025. Two independent researchers identified randomized controlled trials (RCTs) of internet-based interventions for perinatal depression. We conducted conventional and two-stage individual participant data meta-analysis (IPDMA). Results Eighteen studies were eligible, and data from nine ( n = 1094 participants) were pooled in IPDMA. We found evidence of a difference in post-treatment depressive symptoms between participants in the internet-based intervention and controls ( SMD = 0.29 [95%CI: 0.03–0.54], small effect size), increase in response ( RR = 1.97 [95%CI: 1.57–2.47]) and remission ( RR = 1.73 [95%CI: 1.38–2.18]). The interventions were effective for anxiety symptoms ( SMD = 0.26 [95%CI: 0.11–0.40]) but not for reliable deterioration ( OR = 0.80 [95%CI: 0.49–1.32]). No modifiers of effectiveness or deterioration, or prognostic factors of adherence were identified. Baseline depressive symptoms and comorbid anxiety were prognostic factors for higher depressive symptoms at post-treatment. Conclusions Internet-based interventions for perinatal depression are effective for depressive and anxiety symptoms in new and expectant mothers. They may be offered to patients regardless of their age, education, relationship status, employment, baseline depressive or anxiety symptoms, previous treatment, number of children, or ethnic minority status, if they wish to follow them. RCTs should collect more information on factors relevant to the perinatal period, such as partner's mental health and pregnancy complications. Study registration Open Science Framework ( https://osf.io/98tms ).