Vitamin D status in infants during the first 9 months of age and its effect on growth and other biochemical markers: A prospective cohort study

Despite food fortification policies in many countries and recommendations for Vitamin D supplementation of at-risk groups, Vitamin D deficiency (VDD) and infantile rickets remain major public health challenges in many developed and developing countries.

Ninety-six participants at birth were enrolled and followed up until 9 months of age. Serum 25OHD was estimated in cord blood at birth and at 14 ± 1 weeks of life. Seventy-seven participants were followed up at 9 months for estimation of serum 25OHD, parathyroid hormone (PTH), alkaline phosphatase (ALP), calcium, and phosphorus. VDD was defined as serum 25OHD <15 ng/mL as per USIOM guidelines.

Serum 25OHD levels at 9 months of age (15.78 ± 8.97 ng/mL) were significantly increased in comparison to the level of 3 months of age (14.04 ± 7.10 ng/mL) and at birth (8.94 ± 2.24 ng/mL). At birth, all the participants (77) were deficient in 25OHD levels. It was found that 16/94 (17%) and 19/77 (24.7%) participants at 3 and 9 months of age, respectively, became Vitamin D sufficient without any Vitamin D supplementation. There was a significant inverse correlation between serum 25OHD and PTH concentration (r= −0.522,P < 0.001), serum 25OHD and ALP (r= −0.501,P < 0.001). It was found that reduction in serum Vitamin D level to <10.25 ng/mL results in a surge of serum PTH.

VDD is common from birth to 9 months of age but incidence decreases spontaneously even without supplementation. Furthermore, a large number of babies may be falsely labeled as Vitamin D deficient with currently followed cutoffs. Hence a new cutoff for VDD needs to be established for neonates and infants.