Fetal folate C677T methylenetetrahydrofolate reductase gene polymorphism and low birth weight.

The aim of this study was to determine if fetal C677T methylenetetrahydrofolate reductase (MTHFR) genotype contributes to low birth weight. The study group consisted of 243 term babies with a birth weight<10th centile for gestational age, with subgroup analyses for those <1st centile. The control group consisted of 132 term babies with a birth weight 3.3-3.8 kg. Odds ratio analyses with 95% confidence intervals (CI) were calculated for carriage of the t allele and overall genotype frequencies. There was no significant difference in carriage of the t allele between study and control groups, odds ratio (OR) 0.79 (95% CI, 0.57-1.09). No differences were observed for frequencies of heterozygote and recessive homozygote genotypes for the two populations. In the subgroup analyses, no statistical differences were observed in the t allele frequency, frequency of the heterozygote or homozygote genotype. Trends were seen and the study suggests that fetal C677T MTHFR genotype may be a factor contributing to birth weight. The potential may exist to influence clinical outcome by maternal folate supplementation.