[Maternal-neonatal vitamin D status and related factors].

OBJECTIVE: To determine the relationship between maternal and neonatal vitamin D status and related factors.

METHOD: Serum 25-(OH)D levels were measured by ELISA in 499 pregnant women at 30 - 37 weeks gestation and in cord blood of their infants born at term (37 - 42 wk gestation) in Southeastern China at 28.9°N latitude. One-way analysis of variance (ANOVA) was used to explore maternal and neonatal vitamin D levels by season. Pearson linear and linear regression of partial correlation was used to analyze the relationship between maternal and neonatal 25-(OH) D levels. The multiple factors related to maternal vitamin D status was assessed by binary logistic regression.

RESULT: The levels of serum 25-(OH)D were (33.0 ± 13.4) nmol/L in mothers and (31.0 ± 12.5) nmol/L in their newborns. Serum 25-(OH)D < 50 nmol/L was shown in 88.8% of mothers and 91.2% of their neonates. Both maternal and neonatal 25-(OH)D levels varied with season (Ps = 0.000). Vitamin D level was the lowest in spring, with the 25-(OH)D concentration < 50 nmol/L in 98.6% of mothers and 99.3% of their neonates. The highest vitamin D level was presented in fall, but there were still 64.0% of mothers and 75.0% of neonates with 25-(OH)D < 50 nmol/L. Except for season, calcium-vitamin D supplement and intake of egg ≥ 600 g per week during pregnancy benefited to improve maternal vitamin D level [25-(OH)D ≥ 50 nmol/L] [OR = 2.3 (95%CI:1.0, 5.3), 3.4 (95%CI:1.2, 9.9) respectively]. There was a positive correlation between maternal and neonatal 25-(OH)D measures in the sample as a whole (r = 0.45, P = 0.000, N = 499), the correlation was of no statistical significance when maternal serum 25-(OH)D was ≤ 25 nmol/L.

CONCLUSION: Hypovitaminosis D was common in late pregnant mothers and their newborns in southeastern China, especially in spring. Vitamin D supplement and intake of vitamin D-rich food were beneficial to improvement of maternal vitamin D level. There was a moderate and positive correlation between maternal and neonatal 25-(OH)D concentrations in this population. The correlation was lost when maternal serum 25-(OH)D ≤ 25 nmol/L.