Comparison of maternal serum calcidiol and microRNA-1323 expression in term and early preterm births

Objective: Preterm birth remains a leading cause of neonatal morbidity and mortality. Maternal vitamin D status and epigenetic regulation may contribute to its pathogenesis. This study aimed to analyze differences in subject characteristics, calcidiol [25(OH)D] levels, and maternal blood microRNA-1323 (miRNA-1323) expression between term and early preterm (28-34 weeks) deliveries. Materials and Methods: An analytical observational study with a comparative cross-sectional design was conducted among 80 parturient women, including 40 term (37-42 weeks) and 40 early preterm deliveries. Calcidiol levels were measured using enzyme-linked immunosorbent assay, and miRNA-1323 expression was analyzed by quantitative reverse transcription polymerase chain reaction with the ΔCq method. Statistical analyses included normality, non-parametric, and correlation tests (p<0.05). Results: Mean maternal calcidiol levels were significantly higher in the early preterm group than in the term group (27.49±9.18 vs. 23.34±9.64 ng/mL; p=0.022), although both remained below the normal range. Median miRNA-1323 expression was also higher in the early preterm group, but not statistically significant (p=0.709). No significant correlation was observed between maternal calcidiol levels and miRNA-1323 expression in either group, indicating that these biomarkers were not directly associated in the present study and supporting further investigation into their individual contributions to early preterm birth. Conclusion: Maternal calcidiol levels differed significantly between term and early preterm deliveries, whereas miRNA-1323 showed a non-significant increasing trend. Both biomarkers may reflect biological changes associated with preterm birth.