Effect of treatment of vitamin D deficiency and insufficiency during pregnancy on fetal growth indices and maternal weight gain: a randomized clinical trial

Objective: To determine whether treatment of low serum vitamin D in pregnant women improves fetal growth indices. Study design: In this open-label randomized clinical trial, 130 Iranian pregnant women (24-26 weeks of gestation) with vitamin D deficiency or insufficiency [25(OH)D <30 ng/ml] were divided at random into an intervention group and a control group. The control group received 200 mg calcium plus a multivitamin (containing vitamin 03 400 U) each day, and the intervention group received 200 mg calcium plus a multivitamin (containing vitamin 03 400 U) each day, plus vitamin D-3 (50,000 U) each week for 8 weeks. At delivery, maternal and cord blood 25(OH)D levels, maternal weight gain, neonatal length, neonatal weight and neonatal head circumference were compared between two groups. Serum vitamin D was measured using enzyme-linked immunosorbent assay. A multivariate regression analysis was performed to examine the independent effect of maternal vitamin D level on fetal growth indices. Results: Mean (standard deviation) length (intervention group: 49 +/- 1.6 cm; control group: 48.2 +/- 1.7 cm; p = 0.001), head circumference (intervention group: 35.9 +/- 0.7 cm; control group: 35.3 +/- 1.0 cm; p = 0.001) and weight (intervention group: 3429 +/- 351.9 g; control group: 3258.8 +/- 328.2 g; p = 0.01) were higher in the intervention group compared with the control group. Mean maternal weight gain was higher in the intervention group compared with the control group (13.3 +/- 2.4 kg vs 11.7 +/- 2.7 kg; p = 0.006). Multivariate regression analysis for maternal weight gain, neonatal length, neonatal weight and neonatal head circumference showed an independent correlation with maternal vitamin D level. Conclusion: Treatment of low serum vitamin D during pregnancy improves fetal growth indices and maternal weight gain. (C) 2013 Elsevier Ireland Ltd. All rights reserved.