Tabriz University of Medical Sciences Journal of Dental Research, Dental Clinics, Dental Prospects 2008-210X 19 2 2025 06 30 Association of prenatal vitamin D concentration with the eruption time of the first primary tooth: A prospective cohort study 83 88 10.34172/joddd.025.41860 EN Fahimeh Kooshki https://orcid.org/0000-0002-0044-3851 Fatemeh Molaasadolah https://orcid.org/0000-0001-6755-4954 Negin Cheraghi https://orcid.org/0000-0002-1396-4736 Journal Article 10.34172/joddd.025.41860 2024 11 06 2025 04 18 Background. The study investigated the association between vitamin D levels during the first and second trimesters of pregnancy and the eruption time of the first primary tooth. Other possible confounders were also assessed, like infants’ birth weight and length and feeding practices. Understanding these factors is crucial for prenatal care strategies to optimize dental development. Methods. Our prospective cohort study recruited 120 mother‒infant pairs. The data on maternal plasma levels of vitamin D during the first and second trimesters of pregnancy were obtained from mothers’ medical records. The eruption times of the first primary teeth were recorded during regular oral examinations of the infants. A multiple linear regression model was developed to analyze the relationship between maternal vitamin D levels and the teething time. Results. No significant correlation was found between maternal vitamin D levels during the first and second trimesters and the time of the first tooth eruption (P=0.594 and P=0.722). However, birth weight had a significant inverse relationship (P=0.042), indicating that higher birth weight resulted in earlier first tooth eruption. Conclusion. The association between maternal vitamin D levels and the time of tooth eruption remains uncertain. However, birth weight is an important determinant of the timing of deciduous tooth eruption, demonstrating a significant inverse relationship. The study’s clinical relevance lies in its contribution to understanding complex prenatal factors that may influence tooth eruption timing, informing healthcare providers about the importance of monitoring birth weight and other potential determinants.