BACKGROUND
Preterm birth is an important cause of death and developmental disorder in neonates.
Vitamin D deficiency has been shown to regulate body inflammatory factor levels that stimulate elevation of uterine contraction
hormones, such as
prostaglandin, thus causing
preterm birth. However, current observations regarding the relationship between
vitamin D and
preterm birth are inconsistent. We performed a nested case-control study to investigate the effect of
vitamin D on
preterm birth. MATERIAL AND METHODS A prospective cohort study included 200 cases of pregnant women in our hospital from May 2013 to May 2015. Blood samples were collected from early, middle, and late stages of pregnancy. Forty-six patients with preterm delivery were compared with age-matched full-term delivery cases (N=92). High performance liquid chromatography-mass spectrometry (HPLC-MS) was used to detect serum levels of 25(
OH)D, 25(
OH)D2, and 25(
OH)D3. Logistic regression was performed to analyze the correlation between 25(
OH)D and risk of
preterm birth. RESULTS No significant difference in age, smoking/drinking, education level, BMI and
vitamin D levels was found between the
preterm birth group and full-term delivery group. No significant difference was found for
vitamin D levels across different stages of pregnancy; no difference in concentration of 25(
OH)D related to
preterm birth risk was found. After adjusting for potentially confounding factors, serum
vitamin D level did not increase the risk of
preterm birth. CONCLUSIONS This study did not found evidence of an increase in
preterm birth risk related to
vitamin D level during pregnancy.