The Correlation Between Vitamin D Levels and Thyroid Functions in Early Pregnancy

Abstract

Vitamin D deficiency (serum vitamin D <10 ng/ml) and thyroid dysfunctions are prevalent issues globally, particularly during pregnancy. Evidence suggests a potential link between thyroid function and vitamin D levels. This study aims to investigate the correlation between serum vitamin D levels and thyroid functions in wome n during the first trimester of pregnancy. The study was conducted retrospectively at a University Education and Research Hospital’s pregnancy clinic, covering data from August 2023 to March 2024. The sample group consisted of first-trimester pregnant women who attended routine pregnancy check-ups and had complete vitamin D levels and thyroid function tests (n=185). The sociodemographic data form and blood serum level assessment forms were used as data collection tools. The data were analyzed using descriptive statistics and correlation analysis. The average age of the pregnant women participating i n our study was 27.6±4.9 years, and the Body Mass Index (BMI) was 25.4±4.8 (overweight). The mean number of pregnancies was 1.13±0.3, and the gestational week was 8.19±1.8. Of the participants, 35 had subclinical hypothyroidism, 37 had thyroiditis, and 113 had normal thyroid functions. The study identified 36 women with normal/adequate vitamin D levels (≥20 ng/ml), 113 with vitamin D insufficiency (10–20 ng/ml), and 36 with vitamin D deficiency (<10 ng/ml). The correlation analysis revealed no significant relationship between the thyroid function tests and vitamin D levels of the pregnant women. It was determined that vitamin D levels do not affect thyroid gland function in the first trimester. © 2025, Yuzuncu Yil Universitesi Tip Fakultesi. All rights reserved.