Association between Vitamin D levels and autoimmune thyroid disease in early pregnancy

OBJECTIVE: To investigate the association between vitamin D and autoimmune thyroid disease (AITD) in early pregnancy. METHODS: Women with a gestational age of <12 weeks who visited the Department of Gynecology and Endocrinology at Longhua District Central Hospital in Shenzhen between January 2022 and December 2024 were enrolled in this study. Participants were grouped based on the results of thyroid autoantibody tests during follow-up. Pregnant women with positive antibodies were defined as AITD group (n = 40). For each participant, one pregnant woman at the same gestational stage with negative antibodies was selected as a matched control (n = 40). Thyroid function, thyrotropin receptor antibody (TRAb), thyroid peroxidase antibody (TPOAb), thyroglobulin antibody (TgAb) and vitamin D levels were collected. One-way analysis of variance (ANOVA) and t-tests were employed to analyze the association between vitamin D and AITD in early pregnancy. RESULTS: No statistically significant differences were observed between the two groups regarding maternal age and gestational week (p > 0.05). Vitamin D levels were significantly lower in patients with AITD in early pregnancy compared to control group (p < 0.05). Vitamin D levels showed a significant negative correlation with TPOAb, TRAb, and TgAb levels (p < 0.05). CONCLUSION: AITD in early pregnancy is associated with vitamin D levels, with a lower vitamin D level being correlated with a higher risk of developing AITD.