The evidence base of interventions to treat antenatal depression: a meta-analysis of randomized controlled trials

Purpose: Antenatal depression (AD) is a mental health condition estimated to affect close to 30% of pregnant people globally. The importance of treating depression in pregnancy is underscored by its downstream impact on both maternal and infant biopsychosocial outcomes, such as preterm birth, low birthweight, and postnatal depression. Despite these outcomes, only 20% of women experiencing AD receive appropriate and timely support and treatment. This meta-analysis is a comprehensive synthesis of RCTs evaluating psychological and non-psychological interventions to treat antenatal depression, conducted as part of the HappyMums project. Methods: Studies were sourced from PubMed, Embase Medline and MIDIRS (via OVID), and were included if they were (a) randomized controlled trials, (b) with pregnant people with, or at risk for depression, (c) consisted of an intervention, and (d) published in English. To estimate efficacy, Standardized Mean Differences (SMDS) were calculated with 95% confidence intervals using the post- intervention Ms and SDs of both the intervention and control groups. The I2 statistic was used as an indicator of variation between studies. Analyses were conducted using the software R Studio. Results: In total, 115 studies were included in the analysis. The pooled effect size of all interventions, compared with all pooled control arms, showed a clear therapeutic effect (SMD = 0.65, 95% CI 0.48; 0.83), although the between-study heterogeneity variance was high (τ2 = 0.78, 95% CI 0.7;1.3). After accounting for outliers, the pooled effect size across 94 treatment arms was still SMD = 0.5 (95% CI, 0.42, 0.56). No significant subgroup differences were found by intervention type and format, or measure used. Conclusion: There are numerous interventions that, on average, are moderately effective in reducing depressive symptomology in pregnancy. Future research should be aimed at addressing how to personalise the choice of treatment and improve treatment outcomes for the individual pregnant person.