BACKGROUND: Vitamin D deficiency or insufficiency in pregnancy is widespread worldwide. Associations between maternal vitamin D levels and anthropometrics of the newborn have been demonstrated in some, but not all studies. The role of maternal vitamin D levels on fetal bone growth is sparsely studied. Our objective was to perform a systematic review on this topic. METHODS: PubMed, EMBASE and Cochrane were searched using the search words [Vitamin D] in combination with [fetal, fetus, intrauterine, or prenatal AND growth, development, bone, femur, or humerus]; [crown-rump length]; or [ultrasonography, prenatal]. Inclusion criteria for review were data on serum 25-hydroxyvitamin D (25(OH)D) during pregnancy and measurement of fetal growth by ultrasound. RESULTS: Of 545 identified publications, five observational studies were included in the final review. The parameters studied were humerus and femur length (FL) and Z-scores, femoral volume, distal metaphyseal femoral cross-sectional area (CSA) , femoral proximal metaphyseal diameter (PMD), femoral mid-shaft diameter (MSD) and crown rump length (CRL). In one study, 25(OH)D was direct associated with FL, in another study 25(OH)D only correlated to femoral and humeral Z-scores when calcium intake was insufficient. The two largest studies found no association between 25(OH)D and FL, but detected a direct association to femoral PMD, and an inverse relation to distal femoral CSA, respectively. CONCLUSIONS: Sparse observational studies suggest that low maternal 25(OH)D may affect fetal bone under certain circumstances, especially in case of simultaneous low calcium intake. Further studies are needed..
Ultrasound in Obstetrics and Gynecology : the Official Journal of the International Society of Ultrasound in Obstetrics and Gynecology, 2014, Vol 44, Issue 6, p. 633-640