Reproductive behaviors, socioeconomic status and risk for postpartum depression: A Mendelian randomization study

Abstract

Background There is a growing body of evidence showing an association between women's reproductive behavior (RB) and socio-economic status (SES) with the incidence of postpartum depression (PPD). However, the causal relationship between these factors and PPD remains unclear. To facilitate timely screening and effective prevention of maternal emotional disorders, we conducted a Mendelian randomization (MR) study to assess causality between RB/SES and PPD. This study aims to provide new insights into the etiology of PPD and inform public health strategies for its prevention and management. Methods A two-sample Mendelian randomization (MR) study was conducted to investigate the causal effects of reproductive behavior (RB) and socio-economic status (SES) on postpartum depression (PPD). Strongly associated genetic variants for each phenotype were selected as instrumental variables using a predetermined threshold. The primary analysis was conducted using inverse variance weighted method, with additional MR methods including MR-Egger, weighted median, and weighted mode estimate. Potential pleiotropy of instrumental variables (IVs) was evaluated using the MR pleiotropy residual sum and outlier (MR-PRESSO) test and MR-Egger regression methods, and outliers were identified by MR-PRESSO. Heterogeneity among IVs was assessed using Cochran's Q statistic. Leave-one-out sensitivity analysis was performed to identify SNPs that significantly impacted the results. This study aims to provide a better understanding of the causal relationship between RB/SES and PPD and inform future prevention and intervention strategies. Result We found a statistically significant association between age of first sexual intercourse , age at first birth, lifetime number of sexual partners, age completed full-time education, Townsend deprivation index at recruitment, and PPD. However, after Bonferroni correction, only earlier age of first sexual intercourse and age completed full-time education remained significantly associated with an increased risk of PPD. These results were reliable and stable and sensitivity analysis showed no violation of the MR assumptions. This study provides important insights into the causal relationship between RB and SES on PPD and highlights the need for targeted interventions to address risk factors for PPD. Conclusions. MR study provides robust evidence that SES/RB play broad impacts on PPD.