Polymorphism in the vitamin D receptor gene is associated with maternal vitamin D concentration and neonatal outcomes: A Brazilian cohort study.

OBJECTIVES: This study evaluated the associations between single-nucleotide polymorphisms (SNPs) of the vitamin D receptor (VDR) gene, maternal vitamin D concentration, and gestational outcomes.

METHODS: The cohort consisted of 270 pregnant women who received prenatal services at basic public healthcare centers in the city of Santo Antônio de Jesus, Bahia, Brazil. For statistical analysis, multiple linear regression was used.

RESULTS: A mean of 72.62 (SD = 31.51) nmol/L for 25-hydroxyvitamin D (25(OH)D) concentrations was found. The mean birth weight was 3.340 g (SD = 0.545 g), and the mean duration of gestation was 38.66 (SD = 1.83) weeks. Pregnant women who were homozygous for the low-frequency allele GG of SNP TaqI had a higher concentration of vitamin D during gestation (β = 14.09 nmol/L; 95% CI = 0.85, 27.34) than the higher frequency homozygotes AA (β = 3.33 nmol/L; 95% CI = -4.37, 11.05). The children of heterozygous women for the ApaI SNP (GA) were born with a lower weight (β = -131.99 g, 95% CI = -258.50, -5.47, P = .04). The heterozygote genotype of the SNP TaqI (CA) decreased the risk of short duration of gestation (β = 0.54 weeks, 95% CI = 0.09, 0.99, P = .01), and the homozygote for the lower frequency allele in the SNP ApaI (CC) showed a negative effect, decreasing the duration of gestation (β = -0.69 weeks, 95% CI = -1.35, -0.26, P = .04).

CONCLUSIONS: The VDR gene is an important genetic predictor of a higher concentration of vitamin D during gestation, low birth weight, and decreasing duration of gestation.