French prenatal Vitamin D recommended supplementation: Enough or not?

OBJECTIVE: To determine the impact of current recommended vitamin D prenatal supplementation on blood cord 25(OH)D level in a French cohort and to determine population at risk of higher needs.

DESIGN AND SETTING: An observational prospective study was conducted in teaching hospital including two large groups of newborns, one born after summer and another after winter period.

PATIENTS AND METHODS: Three hundred and ninety-nine mother/newborns pairs were enrolled and blood cord results were available for 225 newborns in the post-summer group and 174 newborns in the post-winter group. Maternal supplementation during pregnancy was recorded from medical notes and questionnaires.

RESULTS: 25(OH)D level were generally low with mean at 50.9±24.7nM. Vitamin D supplementation was prescribed in only 37.6% over all the study period. Studying general population, 25(OH)D was significantly higher in the supplemented group, but current recommended supplementation failed to cover the needs for most subgroups of newborns. After winter, 25(OH)D cord blood level was in deficiency range for 40.7% of the general population and in the pigmented mothers group the deficiency rates even rose up to 61.9%.

DISCUSSION AND CONCLUSION: Vitamin D cord level is low in north of France as in other industrial countries. Despite national guidelines on vitamin D supplementation, the rates are currently insufficient. Beside, although the recommended 100,000IU single dose helps to limit deficiency in newborns, it fails to cover infant's needs for optimal status. Actually, benefit of this substitution is for children below the 10th percentile weight. A new recommendation with higher rate of vitamin D for all pregnant women after specific studies seems to be indicated.