Vitamin D Status of Low Birth Weight Infants in Delhi: A Comparative Study

Objective: To evaluate vitamin D status of preterm and term low birthweight (LBW) and term normal birth weight (NBW; weight >= 2500 g) infants at birth and in early infancy. Methods: We enrolled 220 LBW and 119 NBW infants along with their mothers. Blood samples of both infants and mothers were taken within 48 h of birth, and that of infants were repeated at 3 months. Serum levels of calcium, phosphate, alkaline phosphatase, 25 hydroxyvitamin D (25OHD) and parathormone (PTH) were estimated using standard tests. Our primary outcome was vitamin D deficiency (VDD; serum 25OHD < 20 ng/ml in mothers and < 15 ng/ml in infants). Other outcomes were raised PTH (> 46 pg/ml), raised AlkP (> 120 U/l in mothers and 420 U/l in infants), and clinical rickets. Findings: VDD was present in 186 (87.3%) of LBW and 103 (88.6%) of NBW infants at birth, and in 77 (60.6%) of LBW and 55 (71.6%) of NBW infants at a median corrected age of 12 and 15 weeks, respectively. VDD was almost universal (93-97%) among mothers of both groups. Raised PTH was present in 138 (63.6%) of LBW and 48 (41.4%) of NBW infants at birth, and in 58 (45.7%) of LBW and 38 (49.3%) of NBW infants at follow-up. Clinical rickets was present in 17 (13.4%) of LBW and 4 (4.9%) of NBW infants at 12-14 weeks of corrected age. Conclusions: High prevalence of VDD in LBW as well as NBW infants with clinical rickets at an early age underlines the need to study the effect of various vitamin D supplementation regimens in these infants to identify the optimal dose.