Could Maternal Vitamin D Concentration Affect Cervical Length in Mid-Pregnancy? A Report From an Iranian Tertiary Center.

Objective: This descriptive-analytic cross-sectional study aimed to figure out whether maternal serum vitamin D concentration correlates with cervical length measurement in mid-gestation or not. Materials and methods: During Jun-Jan 2021, 213 pregnant women at 18-22 weeks of gestation were investigated. First, demographic features were obtained then, maternal serum vitamin D concentration was measured by enzyme-linked immunoassay and cervical length was measured via transvaginal sonography according to fetal maternal foundation guideline and appropriate statistical test was used to analyze the correlation between maternal vitamin D level and cervical length in mid-pregnancy. Results: It was shown that 29.6% and 25.4% of participants had vitamin D deficiency and insufficiency, respectively. Spearman's test found no significant correlation between maternal vitamin D level and cervical length in mid-pregnancy. Moreover, cervical length and maternal vitamin D level had no association with maternal BMI. Conclusion: Although maternal vitamin D level and its sufficiency status was not associated with cervical length in mid-pregnancy, as a trend toward decreased maternal serum vitamin D level by advancing gestational age was observed. It may be concluded that it is prolonged vitamin D deficiency during gestation that may lead to cervical length shortening and subsequent preterm delivery later in gestation.