A thyroid antibody flags 52% higher risk of depression around pregnancy

Perinatal depression affects a substantial subset of women worldwide, and it carries real consequences: the abstract notes significant risks to maternal and infant health and to how children develop afterwards. Anything that helps identify who is most at risk before symptoms take hold would be valuable, because depression around pregnancy is often missed. Thyroid peroxidase antibodies, a marker of autoimmune activity against the thyroid gland, have long been suspected of playing a role, but the evidence connecting them to perinatal depression has been inconsistent. This analysis set out to settle whether that connection actually holds up when all the available studies are weighed together.

The researchers systematically searched five major databases, PubMed, Web of Science, Embase, the Cochrane Library and PsycINFO, from their inception up to 1 March 2025. They included cohort, case-control and cross-sectional studies that examined the relationship between thyroid peroxidase antibody positivity and the risk of perinatal depression, following the PRISMA 2020 checklist throughout. Two quality safeguards were built in: the risk of bias in each study was scored using the Newcastle-Ottawa Scale, and the results were pooled using both random-effects and fixed-effects statistical models. After screening, 11 studies covering 10,559 patients met the criteria and were combined.

The headline result was clear in direction: women who tested positive for thyroid peroxidase antibodies had a significantly higher risk of developing perinatal depression, with a pooled relative risk of 1.52, meaning roughly a 52% higher risk than antibody-negative women. The statistical range around that estimate ran from 1.16 to 1.99, so the true effect could be smaller or larger than the central figure. The included studies disagreed with each other to a moderate degree, which the authors flag as a limitation. They also note that the number of eligible studies was limited, and they stop short of claiming the antibody causes depression.

Before this analysis, the evidence on thyroid antibodies and perinatal depression was described by the authors themselves as uncertain, with individual studies pointing in different directions. Pooling 11 of them gives the association firmer footing than any single study could, and it adds perinatal depression to the list of outcomes connected to thyroid autoimmunity. But important questions stay open. The included studies measured antibody status at varying points, and the authors call for prospective studies that assess antibody positivity at specific time points during pregnancy. Whether treating or monitoring thyroid autoimmunity would change depression risk remains completely untested here.

For anyone who is pregnant, planning a pregnancy, or supporting someone who is, this is a reason to think of thyroid autoimmunity as one possible marker of mental health risk around pregnancy, alongside the better-known ones. Thyroid peroxidase antibodies are detected with a standard blood test, so the association is at least built on something measurable rather than obscure. It is worth holding the finding lightly: this research followed groups of women rather than testing an intervention, so it cannot say the antibody causes low mood, and a positive test is far from a prediction. What it does suggest is that thyroid and mental health around pregnancy may be more connected than commonly assumed.