D'Souza et al share some interesting thoughts regarding our article on the effects of folic acid supplementation in the second and third trimesters of pregnancy (1). They point out, quite rightly, that whereas folic acid supplementation influenced maternal homo-cysteine by preventing the increase in homocysteine usually observed in the third trimester (2), we did not observe a difference in cord blood homocysteine concentrations between the placebo and folic acid treatment groups. D'Souza et al suggest that low vitamin B-12 status might explain the anomaly. Serum total vitamin B-12 is known to decrease by approx30 over the course of pregnancy (3), and in this study between gestational weeks 14 and 36 we observed (although did not report) a decline in maternal vitamin B-12 concentrations of 22 (from 211 +- 82 pmol/L to 165 ± 59 pmol/L; P = 0.001) in the placebo group and 25 (from 235 ± 94 pmol/L to 176 ± 75 pmol/L; P = 0.001) in the folic acid-supplemented group, with no significant treatment effect (P = 0.59). We interpret this as indicating that vitamin B-12 affected the relation between maternal and cord blood homocysteine in both groups, although this was not an outcome of primary interest to the study.
展开▼
