Subclinical hypovitaminosis D among exclusively breastfed young infants.

OBJECTIVE: To determine Vitamin D status of mother-newborn diads at birth and of their exclusively breastfed (EBF) infants at 3 months.

DESIGN: Longitudinal study.

METHODS: Exclusively breastfed infants born at term with birth weight > 2.5 kg to normal, healthy mothers followed till 3 months. Serum calcium, phosphorous, heat labile alkaline phosphatase (HLAP) and 25(OH)D estimated in 42 mother / cord blood diads and in 35 (EBF) infants followed up at 3 months. Twenty five (OH)D < 15 ng/mL was considered low and 15 to 25 ng/mL low to normal.

RESULTS: Ca, P, HLAP were significantly higher in cord blood (P < 0.001) but mean 25 (OH)D, 19.36 ng/mL was comparable to maternal level of 22.9 ng/mL (r = 0.82, P < 0.001). At 3 months only HLAP was significantly higher compared to cord blood. Higher 25 (OH)D at 3 months correlated with higher 25 (OH)D values in cord blood (r = +0.616, P < 0.001) as well as higher antenatal maternal levels (r = + 0.552, P < 0.001). Serum 25 (OH)D values < 25 ng/mL was observed in 50 % mothers, 62 % cord blood specimens and 80 % infants at 3 months.

CONCLUSIONS: Subnormal maternal vitamin D status is associated with vitamin D deficiency in newborns and persists in exclusively breastfed infants.