Thyroid autoimmunity and risk of post-partum depression: a systematic review and meta-analysis of longitudinal studies

Purpose The aim of this study was to systematically investigate whether, and to what extent, the detection of thyroid autoimmunity during pregnancy and in the weeks after childbirth is associated with an increased risk of developing post-partum depression (PPD), a condition associated with possible adverse outcomes for both mother and offspring. We performed a systematic review and meta-analysis of longitudinal studies, assessing the incidence of PPD in women with and without anti-thyroperoxidase antibody (TPOAb) positivity. Methods We searched MEDLINE, EMBASE, Web of Science, Cochrane Library, and CINAHL. Methodological quality of the studies was assessed by the Newcastle-Ottawa Scale. In the presence of even modest between-studies heterogeneity, assessed by Cochrane Q and I-2 tests, risk ratios (RRs) for PPD were combined using a random effects model. Funnel plot and trim-and-fill analysis were used to assess publication bias. Results Five included studies provided information on 449 women with TPOAb-positive and 2483 TPOAb-negative women. Pooled RR indicated a significantly increased risk to develop PPD in TPOAb-positive group (RR 1.49, 95% CI 1.11-2.00; P = 0.008; I-2 = 47%, P-for heterogeneity = 0.11). Consistent with a possible publication bias, the trim-and-fill test detected two putative missing studies in the funnel plot. Nevertheless, the adjustment for publication bias produced a negligible effect on the pooled estimate (adjusted RR 1.41, 95% CI 1.18-1.68, P = 0.0002). Conclusions Thyroid autoimmunity during pregnancy and in the weeks after childbirth is associated with an increased risk of developing PPD. Further well-designed studies are warranted to confirm this association and elucidate underlying pathophysiological mechanisms. PROSPERO registration CRD42019129643.