Maternal Vitamin D Deficiency and Fetal Growth

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ABSTRACT There is increasing incidence of vitamin D deficiency in pregnancy in developed countries. Dark skinned women who have migrated and live in higher latitudes are at greatest risk. Vitamin D supplementation is now recommended in several countries, yet its impact on fetal growth remains unclear. Observational studies suggest a possible correlation between maternal serum vitaminD and birth weight. However, differences in birth weight can be confounded by soft-tissue growth and placental function. The effect on vitamin D on bone mineral indices using dual energy X-ray absorptiometry is difficult to ascertain in the neonatal period and therefore remains unclear. Prenatal ultrasound is a safe and practical modality for assessing skeletal growth, yet very few studies have investigated fetal growth in the context of vitamin D status: one study has demonstrated no correlation with femur length, whereas two studies have shown positive correlations with femur length and femur volume respectively. The effect of vitamin D supplementation on birth weight has been investigated in seven interventional studies. However, there is considerable methodological heterogeneity and high risk of bias among some of them. Meta-analysis of well conducted randomized controlled trials (RCTs) has not demonstrated a significant effect on birth weight. The effect of vitamin D supplementation on ultrasound markers of fetal growth has not been reported to date. In summary, there is weak evidence that maternal vitamin D status may have a positive association with measures of fetal skeletal growth. However, if such an association exists, it is not clear whether it is causal or spurious. Randomized controlled trials of vitamin D supplementation are needed, where fetal ultrasound and neonatal bone mineral indices will be reported as primary outcome measures. How to cite this article Ioannou C. Maternal Vitamin D Deficiency and Fetal Growth. Donald School J Ultrasound Obstet Gynecol 2015;9(3):223-229.