Vitamin D Status and Calcium Homeostasis in Mother and Newborn Dyad: A Hospital Based Study from South Delhi

Studies in the 2000s in India showed a high prevalence of vitamin D deficiency in apparently healthy pregnant women and their newborns. With awareness about sunshine exposure and vitamin D supplementation, vitamin D deficiency would have declined over the last two decades. We assessed current vitamin D status of maternal-newborn dyads at a teaching institute in Delhi.

The study included 104 pregnant women (27.8 ± 4.2 yrs) and their singleton healthy term newborns (M: F = 63:41) delivered at HIMSR Delhi during years 2023-25. Cord-blood was drawn at delivery, and fasting maternal blood was drawn for serum total calcium, phosphate, alkaline phosphatase, 25(OH)D, and intact-PTH assessment. Serum 25(OH)D and PTH were measured by chemiluminescence assay.

The median (IQR) serum 25(OH)D of mothers and newborns was 11.8 (6.9-19.1) and 13.7 (7.9-24.7) ng/mL, respectively. Serum 25(OH) was <12 ng/mL in 51% of mothers and 44% of newborns. Maternal and cord-blood 25(OH)D correlated significantly (r = 0.945, P < 0.001). Maternal serum 25(OH)D correlated inversely with iPTH (r = -0.400, P < 0.01). Maternal and cord-blood iPTH showed no significant correlation. Serum calcium (9.1 ± 1.2 vs. 10.9 ± 1.1 mg/dL, P < 0.001) and phosphate (4.4 ± 0.9 vs. 6.2 ± 1.1 mg/dL, P < 0.001), were lower in mothers than newborns unlike alkaline phosphatase (200 ± 77 vs. 138 ± 39 IU/L, P < 0.001) which was higher in mothers. Serum phosphate was significantly lower in male than female newborns, while 25(OH)D and total calcium were comparable.

A high prevalence of vitamin D deficiency in mothers and newborns was observed, despite two decades of awareness. This emphasizes for more targeted and proactive public health initiatives to combat maternal and neonatal hypovitaminosis D.