Vitamin D status at birth among pregnant women and their newborns in Jordan: a cross-sectional study

Background Growing evidence suggests a link between vitamin D deficiency during pregnancy and an increased risk of adverse pregnancy and birth outcomes. Objective This study aimed to measure serum 25-hydroxyvitamin D (25[OH]D) concentrations in pregnant women and their newborns and to explore potential associations between vitamin D levels and maternal and neonatal factors. Methods This cross-sectional study was conducted at King Abdullah University Hospital (KAUH) in Jordan. A total of 396 pregnant women who gave birth between November 2021 and July 2022 were recruited. Maternal and cord blood samples were collected at the time of delivery, and serum vitamin D concentrations were measured using an enzyme-linked immunosorbent assay (ELISA). The Mann–Whitney U test and Spearman’s correlation test were used for statistical analysis. A multivariable linear regression analysis was performed to identify independent predictors of maternal and cord blood vitamin D levels. A p -value of < 0.05 was considered statistically significant. Results The median maternal and cord blood serum vitamin D levels were 9.86 [8.32–11.17] ng/mL and 10.12 [8.58–11.01] ng/mL, respectively. Vitamin D concentrations were below 20 ng/mL in 99.7% of maternal blood samples and 99.5% of cord blood samples. Only 76 women (19.1%) reported vitamin D supplementation during pregnancy, with a mean daily intake of 1,052.9 international units. Maternal and cord blood serum vitamin D levels were positively associated (Spearman’s rho = 0.357, CI: 0.267–0.440, p < 0.001). Maternal serum vitamin D levels were higher among women who delivered in summer than among those who delivered in winter (11.76 [10.87–12.41] ng/mL vs. 9.39 [7.71–10.19] ng/mL, CI: 1.845–3.133, p < 0.001). Cord blood serum vitamin D levels were also higher among neonates born in summer than among those born in winter (10.65 [10.14–11.42] ng/mL vs. 9.63 [8.02–10.74] ng/mL, CI: 0.441–2.023, p = 0.002) and lower in small-for-gestational-age (SGA) neonates than in non-SGA neonates (9.3 [6.70–10.51] ng/mL vs. 10.19 [8.76–11.05] ng/mL, CI: −2.124 to −0.018, p = 0.046). Conclusion Vitamin D insufficiency was highly prevalent among pregnant women and newborns in this Jordanian cohort. Further evaluation of targeted screening, appropriate supplementation strategies, and public health interventions is warranted. Clinical trial registration ClinicalTrials.gov , Identifier NCT04944212.