A Good Dose of Vitamin D

Vitamin D supplementation for pregnant women and infants improves overall levels

(RxWiki News) One of the goals of good prenatal care is to ensure babies get all the nutrients they need as they develop in the womb. Woman may take certain supplements to achieve this goal.

A recent study found that vitamin D supplements for pregnant women and their newborns ensured sufficient vitamin D levels in more of the children than those without supplements.

Vitamin D is currently added to some foods since it is harder than many other nutrients to get through diet alone.

Some women may need to take vitamin D supplements to ensure they and their children have sufficient levels.

However, this decision about supplements should be made with a doctor's supervision since too much vitamin D can have negative side effects.

"Ask your OBGYN about vitamin D supplements."

The study, led by Cameron C. Grant, PhD, of the department of pediatrics at the University of Auckland in New Zealand, aimed to determine the best way to ensure babies have appropriate vitamin D levels.

The researchers divided 260 women who were 27 weeks pregnant into three groups.

One group of 87 women received 1000 IU daily of vitamin D until they gave birth, and then their babies were given 400 IU daily of vitamin D until they were 6 months old.

The second group of 86 pregnant women received 2000 IU daily of vitamin D, and their babies were given 800 IU daily of vitamin D until 6 months old.

The third group of 87 women received a placebo (fake vitamin) during the study, and then their children also received a placebo through 6 months old.

The researchers measured the vitamin D levels in the women at the start of the study and when they were 36 weeks pregnant.

The children's vitamin D levels were measured at 2 months, 4 months, and 6 months old.

At the start of the study, 54 percent of the women who had received placebos had vitamin D levels of at least 20 ng/mL in their blood.

Having at least 20 ng/mL of vitamin D was determined in 2011 by the Institute of Medicine to be sufficient vitamin D levels for at least 98 percent of children under 1 year old.

At 36 weeks of pregnancy, 50 percent of the placebo group had vitamin D levels of at least that much.

Meanwhile, the other two groups saw significant increases in the percentage of women who had higher vitamin D levels after receiving supplements.

Among the group that had received 1000 IU a day of the vitamin, 64 percent had at least 20 ng/mL of vitamin D in their blood at the start of the study. At 36 weeks of pregnancy, 91 percent of that group had those levels of vitamin D.

While 55 percent of the group receiving 2000 IU a day had at least 20 ng/mL of vitamin D in their blood at the start of the study, 89 percent of the women in that group had those levels at 36 weeks of pregnancy.

At birth, 22 percent of the newborns in the placebo group had cord blood levels of vitamin at 20 ng/mL or greater.

Meanwhile, 72 percent of the newborns whose mothers had received 1000 IU vitamin D daily, and 71 percent of the newborns whose mothers received 2000 IU daily had at last 20 ng/mL of vitamin D in their cord blood.

At 2 months old, 50 percent of the babies in the placebo group, 82 percent of the babies in the 400 IU daily group, and 92 percent of the babies in the 800 IU daily group had vitamin D levels of at least 20 ng/mL.

At 4 months old, 66 percent of the babies in the placebo group, and 87 percent of the babies in both of the vitamin D supplement groups had at least 20 ng/mL of vitamin D in their blood.

By the time the babies were 6 months old, however, only the group receiving 800 IU of vitamin D daily had a significantly greater percentage of babies with the higher vitamin D levels.

At 6 months old, 74 percent of the placebo babies, 82 percent of the babies receiving 400 IU daily, and 89 percent of the babies receiving 800 IU daily had vitamin D levels of at least 20 ng/mL.

The researchers therefore concluded that vitamin D supplementation in pregnant women and their babies increased the percentage of infants that had appropriate vitamin D levels.

The researchers did not observe hypercalcemia in either group of women and children receiving vitamin D supplements.

Hypercalcemia is a condition in which a person has abnormally high levels of calcium in their body, which can be caused by too much vitamin D intake.

"If the objective of vitamin D supplementation is to achieve a serum 25(OH)D concentration >20 ng/mL in 97.5 percent of infants, then it seems likely that this requires both maternal vitamin D supplementation during pregnancy and high compliance with daily dosing regimens," the authors wrote.

However, this study's findings do not mean that women or their children necessarily need to take vitamin D supplements, cautions Andre Hall, MD, an OBGYN at Birth and Women's Care, PA in Fayetteville, NC.

"While I do not question that adding vitamin D supplementation above and beyond prenatal vitamins and diet will increase the levels in children, I do question whether it's necessary or even potentially harmful," Dr. Hall said.

"Pregnant women often do not eat diets that are sufficient to provide all the necessary nutrients for themselves and their developing child," he explained. "Hence, prenatal vitamins are prescribed and strongly recommended prior to conception and during the pregnancy."

Dr. Hall said the many brands of prenatal vitamins are all required by the Food and Drug Administration to contain a certain amount of different vitamins and minerals.

"Therefore, in my opinion, regardless of cost, they are all equally adequate in providing the appropriate nutrients," he said. "Therefore, I do not recommend adding additional supplements above and beyond what will be obtained from a regular diet and daily prenatal vitamin usage."

The study was published December 16 in the journal Pediatrics.

The research was funded by the Health Research Council of New Zealand and Cure Kids. The study medication was prepared by the Ddrops Company. The authors declared no conflicts of interest.

Review Date: 
December 16, 2013