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Most Preterm Infants May be Insufficient in Vitamin D

But High Amounts of Supplement Appear to be Safe and Effective

Sunday, April 29, 2012

Nearly two-thirds of preterm infants are insufficient in vitamin D at birth but high amounts of vitamin D supplementation in pregnant women appear to be safe and effective in raising vitamin D levels to normal – in babies and their mothers, according to two studies being presented this week.

Previous research has suggested that vitamin D deficiency during pregnancy may impair fetal growth and increase the risk of respiratory infections in infancy.

The new studies, conducted by researchers at Cincinnati Children’s Hospital Medical Center, will be presented April 28 and 29 at the annual meeting of the Pediatric Academic Societies in Boston.

“Vitamin D deficiency in pregnancy is a global health problem, and the amount of supplementation to prevent deficiency and insufficiency is controversial,” says Adekunle Dawodu, MD, a physician in the division of Global Health at Cincinnati Children’s who took part in both of the new studies. “The Institute of Medicine recommends 600 IU (International Units) daily in pregnant and lactating women. But we found that 2000 to 4000 IU a day appears to be safe in pregnant women, and 4000 IU a day is most effective in achieving optimal vitamin D levels in mothers and their infants.”

The first Cincinnati Children’s study looked at 120 preterm infants at three newborn intensive care units in the United States. Approximately two-thirds were vitamin D deficient at birth, using the standard test for measuring vitamin D levels in individuals. At current recommended levels of supplementation of vitamin D, about 40 percent remained deficient at four weeks chronological age and what would have been the 36th week of pregnancy.

The second study was conducted in the United Arab Emirates, where there is endemic vitamin D deficiency in women, in part due to the hijab – a dress practice that emphasizes modesty and thus prevents skin exposure to sun. Nearly 200 Arab women enrolled in the study, which was intended to determine the safety and effectiveness of differing level of maternal vitamin D supplementation. Supplementation of 4000 IU a day was most effective in preventing vitamin D deficiency in both mothers and their infants.

The researchers believe this finding would apply to other populations where vitamin D deficiency is endemic.

The human body produces vitamin D in response to sunlight. Vitamin D also occurs naturally in some foods and in fortified dairy and grain products. It is essential for strong bones because it helps the body use dietary calcium. Traditionally, vitamin D deficiency has been associated with rickets, a disease in which the bone tissue doesn't properly mineralize, leading to soft bones and skeletal deformities. Increasingly, however, research has revealed that vitamin D deficiency is associated with a host of other health problems.

The first study was conducted by Nagendra Monangi, MD, a fellow in the division of Neonatology, Perinatal and Pulmonary Biology at Cincinnati Children’s, under the mentorship of Henry Akinbi, MD, and Dr. Dawodu. Dr. Dawodu also led the study conducted in the United Arab Emirates.