Effect of vitamin D supplementation during pregnancy on foetal growth. Effect of calcium and vitamin D supplementation on toxaemia of pregnancy. Vitamin D supplementation in pregnancy: a controlled trial of two methods. Vitamin D supplementation during pregnancy: effect on neonatal calcium homeostasis.
nan To study the effect of calcium and vitamin D supplementation on the incidence of toxaemia of pregnancy, 200 randomly selected pregnant women (supplemented group), were put on calcium (375 mg/day) and vitamin D (1,200 IU/day) supplements at 20-24 weeks of pregnancy onwards. Another 200 pregnant women constituted the non-supplemented group. At 32 and 36 weeks of pregnancy the systolic and diastolic blood pressure of non-toxemic women was significantly lower in the supplemented group than in the non-supplemented group. However, the incidence of toxaemia in the supplemented group (6%) was not significantly different from that in the non-supplemented group (9%). A randomized study was conducted to evaluate the effects of single-dose and daily vitamin D supplementation in pregnant women during the last trimester of a winter pregnancy in the Northwest of France. The women were divided into three randomized groups: one (N = 21) was given a vitamin D2 supplement of 1000 IU/day during the last three months of pregnancy, one (N = 27) was given a single oral dose of 5 mg at the seventh month of pregnancy, and one (N = 29) acted as a control. Venous plasma samples were obtained at delivery from the women and from cord blood, and levels of calcium, 25-OHD, and 1,25(OH)2D were determined. No significant difference in plasma calcium concentration was found among the three groups, but within each group plasma calcium concentrations were higher in the cord samples than in the respective maternal samples. The levels of the two metabolites measured were consistently lower in the cord samples than in the respective maternal samples. Cord 25-OHD concentrations correlated with those of maternal plasma. No significant modification of maternal calciuria or of the birth weight of term infants was observed. 25-OHD concentrations were greater in maternal and cord plasma from treated mothers, but only a slight difference was observed between the supplemented groups. 1,25(OH)2D concentrations were not significantly different in the three groups. A single 5-mg dose of vitamin D given orally at the seventh month of pregnancy provides effective prophylaxis in the authors' region. We assessed whether modification of vitamin D nutritional status during the last trimester of pregnancy affects maternal and neonatal calcium homeostasis. At the end of the first trimester, 40 pregnant women were randomly assigned to either of two groups, and blood taken to assess the basal values of Ca, Pi, Mg, iPTH, 25-OHD, and 1,25(OH)2D. From the sixth month on, group 1 (+D) received 1000 IU vitamin D3 daily; group 2 (-D) served as control. At the time of delivery, maternal serum 25-OHD was higher in the +D group (P less than 0.0005). Ca, Pi, iPTH, and 1,25(OH)2D were not affected. At term, venous cord 25-OHD levels were also higher in the +D group (P less than 0.0005), and 1,25(OH)2D levels slightly lower (P less than 0.05), but neither Ca, Pi, nor iPTH differed between the two groups. Serum CaT dropped significantly (P less than 0.002) at 4 days of age in the infants from both groups, although to a lesser extent in these from the +D group (P less than 0.05). Circulating iPTH increased in both groups. Serum 25-OHD remained low in the -D group, and dropped slightly in the +D group; 1,25(OH)2D remained stable during the first 4 days of life in the -D group, and increased in the +D group (P less than 0.001). Our data demonstrate the importance of providing adequate maternal vitamin D stores to ensure better perinatal handling of calcium. This is of particular importance for populations at risk for hypovitaminosis D.
Vitamin D supplementation in a single or continued dose during pregnancy increases serum vitamin D concentrations as measured by 25-hydroxyvitamin D at term. The clinical significance of this finding and the potential use of this intervention as a part of routine antenatal care are yet to be determined as the number of high quality trials and outcomes reported is too limited to draw conclusions on its usefulness and safety. Further rigorous randomised trials are required to evaluate the role of vitamin D supplementation in pregnancy.