PITTSBURGH, Pa.—Results from a recent study suggest vitamin D has a complex relation with fetal growth that may vary by race (J Nutr. 2010;140(5):999-1006). The University of Pittsburgh conducted a study investigating maternal vitamin D deficiency and it association with fetal growth, specifically, maternal serum 25-hydroxyvitamin D [25(OH)D] concentrations in early pregnancy and the risk of small-for-gestational age birth (SGA) and the association between maternal single nucleotide polymorphisms (SNP) in the vitamin D receptor (VDR) gene and the risk of SGA.
Researchers conducted a nested case-control study of nulliparous pregnant women with singleton pregnancies who delivered SGA infants (n=7 white, n=34 black) or non-SGA infants (n=196 white, n=105 black). Women were followed from less than16 weeks of gestation to delivery. SGA was defined as live-born infants less than the 10th percentile of birth weight according to nomograms based on gender and gestational age.
After confounder adjustment, there was a U-shaped relation between serum 25(OH)D and risk of SGA among white mothers, with the lowest risk from 60 to 80 nmol/L. There was no relation between 25(OH)D and SGA risk among black mothers. One SNP in the VDR gene among white women and 3 SNP in black women were significantly associated with SGA.