Vitamin D reduced pregnancy risks

VANCOUVER, British Columbia — Mothers who took high doses of vitamin D during pregnancy experienced lower preterm labor, preterm birth and infection rates compared with mothers who did not, according to a speaker at the 2010 Pediatric Academic Societies Annual Meeting.

In the past, some worried that vitamin D caused birth defects, said Carol L. Wagner, MD, of the Medical University of South Carolina, in Charleston. However, recent research supports the importance of vitamin D in promoting bone health and immune function for both mothers and babies.

Wagner and colleagues conducted a randomized controlled trial to determine the optimal dose of vitamin D supplements for pregnant women without causing harm. They randomly assigned 494 pregnant women at 12- to 16- weeks gestation to 400 IU (control group; n=111), 2,000 IU (n=122) or 4,000 IU (m=117) of vitamin D per day until delivery; 350 women continued to delivery.

After performing logistic regression analyses to determine the effects of vitamin D on preeclampsia, gestational diabetes, infections and preterm labor and birth, the researchers determined that women who took the highest of these three daily doses had half the risk for co-morbidities than the control group (RR=0.50; 95% CI, 0.27-0.95; P=.03).

“No adverse events related to vitamin D dosing were found in any of the three arms of the study,” Wagner said, noting that more detailed safety data will be presented here tomorrow.

Based on these findings the researchers recommended a daily regimen of 4,000 IU a day for all pregnant women, an increase from current recommendations that state that infants should receive 400 IU a day, children, 200 IU and adults older than 70 years, 600 IU.

“Diet doesn’t provide enough vitamin D, and we don’t go in the sun as much as we need,” Wagner said.

The researchers observed several other significant effects among the study groups attributable to vitamin D supplements:

Mean 25-hydroxyvitamin D (25(OH)D) were significantly different between the control group and each of the groups that received vitamin supplements at delivery and one month before (P<.0001).
Serum 25(OH)D levels had a direct influence on calcitriol (1,25(OH)₂D) levels throughout pregnancy ( P<.0001) with 40 ng per mL of 25(OH)D for maximum calcitriol production.
Rates of pre-term labor, pre-term birth, and infection were inversely related to 25(OH)D levels and were lowest in the 4,000 IU group (P<.0001), after adjusting for race.
In women without comorbidities 25(OH)D levels were 33.4 ng per mL vs. 39.0 ng per mL in those women without (P<.008).

Additionaly, neonatal serum 25(OH)D levels were significantly correlated with maternal 25(OH)D levels overall, a month before delivery and at delivery, according to Wagner.

On average, babies born to the control group had 18.2 ng serum 25(OH)D per mL, compared with 22.8 among babies born to mothers who took 2,000 IU daily supplements and 26.5 among babies born to the 4,000-IU women. – by Nicole Blazek

For more information:

Wagner CL. #1665.6. Presented at: 2010 Pediatric Academic Societies Annual Meeting; May 1-4, 2010; Vancouver, British Columbia.

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