Preterm infants may need 800 IU of vitamin D3 per day

Preterm infants may need to be given 800 international units (IU) of vitamin D a day to ensure they develop strong bones, according to a study to be presented Sunday, May 5, at the Pediatric Academic Societies (PAS) annual meeting in Washington, DC.

Preemies are known to be at risk for vitamin D insufficiency. If levels of vitamin D are too low, infants and children can get rickets, which leads to softening and weakening of the bones.

Recommendations from medical organizations on how much vitamin D should be given to preemies range from 400 IU to 1000 IU per day. This lack of consensus prompted researchers from All India Institute of Medical Sciences, New Delhi, to conduct the largest study to date on vitamin D supplementation in preterm infants.

Subjects included 96 infants born between 28 and 34 weeks' gestation who were receiving milk feeding. Blood samples were taken from the infants to determine their serum vitamin D levels. The infants then were randomly assigned to receive either 800 IU or 400 IU of oral vitamin D3. Neither the parents nor the primary investigator was aware of which dose the infants were receiving.

Researchers compared whether the prevalence of vitamin D insufficiency (VDI) at 40 weeks and at 3 months corrected age differed between the groups. They also looked at whether infants with higher vitamin D levels also had stronger bones at 3 months corrected age and whether supplementation led to vitamin D levels that were too high.

Results showed that VDI was common in both groups before they received supplements (79 percent of the 800 IU group and 83 percent of the 400 IU group).

After supplementation, the prevalence of VDI at 40 weeks was 43 percent lower in the 800 IU group than the 400 IU group (38 percent vs. 67 percent). In addition, VDI was significantly lower in the 800 IU group when the infants were 3 months old (12 percent vs. 35 percent).

Vitamin D supplementation is recommended for preterm infants both while they are still in the hospital and after discharge, according to dietary guidelines issued in a clinical report published online April 29 in Pediatrics. Calcium and phosphorous supplementation is also recommended early on.

Steven A. Abrams, MD, professor of pediatrics at Baylor College of Medicine in Houston, Texas, developed the guidelines along with the American Academy of Pediatrics Committee on Nutrition.

The guidelines contain the first dietary recommendations for vitamin D and calcium intakes specifically designed for preterm infants, who "have unique bone mineral requirements that may not be assumed to be similar to those of full-term newborn infants," the authors write. Institute of Medicine dietary guidelines issued in 2011 for calcium and vitamin D intake did not include recommendations for preterm infants.

Key elements to help prevent rickets in very low birth weight (VLBW) infants are absorbed calcium and phosphorous, the authors write, and unfortified human milk, parenteral nutrition, and infant formulas do not contain enough of these minerals to promote healthy bones in these infants. Vitamin D helps the infants absorb calcium.