Evaluation of pregnant women's awareness level of iodine supplementation and investigation of factors affecting breast milk iodine levels

Introduction: Iodine is a vital micronutrient for fetal development, neurological function, and thyroid hormone synthesis. Iodine deficiency during pregnancy can lead to preventable intellectual disabilities. Breast milk iodine concentration (BMIC) is a key indicator of maternal iodine status and infant iodine intake. Objective: This study aimed to assess pregnant women's awareness of iodine supplementation, measure BMIC, and identify factors influencing BMIC to better understand and prevent iodine deficiency-related developmental issues. Method: A cross-sectional study was conducted with 201 postpartum women at Istanbul University-Cerrahpaşa. BMIC was measured using inductively coupled plasma mass spectrometry (ICP-MS). Awareness levels were evaluated through structured face-to-face questionnaires. Statistical analyses were performed using SPSS v.26, with significance set at p<0.05. Results: The median BMIC was 748.19 μg/L, with 74% of participants exceeding the WHO threshold of 400 μg/L. Cesarean deliveries were associated with significantly higher BMIC compared to vaginal births (p=0.000), likely due to exposure to povidone-iodine (PVP-I). Smokers had significantly lower BMIC than non-smokers (p=0.04). Although 10 infants had elevated TSH levels at neonatal screening, 8 normalized during follow-up. A positive correlation was found between BMIC and TSH levels, particularly in infants screened between days 3–7. Conclusion: High BMIC levels, especially in cesarean deliveries, may be influenced by PVP-I exposure. Smoking negatively impacts BMIC. While temporary BMIC elevation does not appear to affect neonatal thyroid function, timing of screening is crucial for accurate interpretation. Awareness of iodine supplementation remains essential for maternal and infant health.