Associations between maternal vitamin D status during three trimesters and cord blood 25(OH)D concentrations in newborns: a prospective Shanghai birth cohort study

Purpose Prenatal vitamin D (VitD) deficiency influences children’s health in later life. We aimed to test the associations between maternal VitD status in each of the three trimesters of pregnancy and cord blood 25(OH)D concentrations in newborns. Methods Participants were pregnant women recruited from the Shanghai Birth Cohort (SBC) ( n = 1100). Of all the participants, 946 completed the collection of venous blood at early (< 16 weeks, T1), mid- (24–28 weeks, T2), and late (32–34 weeks, T3) pregnancy as well as the corresponding cord blood in the newborns. Maternal serum 25(OH)D concentrations were measured by LC–MS/MS, and the information on confounding factors was obtained through a standardized questionnaire. Results The mean 25(OH)D concentrations at time points T1, T2, T3 in maternal blood and cord blood of the newborns were 26.31 ng/mL, 31.92 ng/mL, 35.62 ng/mL, and 19.77 ng/mL, respectively. Neonatal 25(OH)D level in cord blood was positively correlated with maternal serum 25(OH)D levels at each trimester, and the strongest correlation was found at time point T3. Conclusion Maternal 25(OH)D concentrations at each trimester were positively associated with neonatal VitD status in cord blood, and the strongest correlation was found in the late stage of pregnancy, which could be considered as a sensitive time window. Attention should be paid to the nutritional status of VitD during pregnancy to better prevent the VitD deficiency in neonates.