Relationship between total homocysteine and folate levels in pregnant women and their newborn babies according to maternal serum levels of vitamin B12

Objective To determine total homocysteine and folate levels in pregnant women according to vitamin B-12 (B-12) levels, and to analyse the impact of maternal B-12 levels on the nutritional status of their newborn babies. Design Cross sectional observational study. Setting Two public hospitals in Jundiai City, Sao Paulo, Brazil. Sample Sixty-nine pregnant women and their respective newborn babies at the time of delivery. Methods Maternal blood was collected up to 8 hours before delivery. Umbilical cord blood was collected after the expulsion of the placenta. Total homocysteine was measured by high performance liquid chromatography, folate by ion capture methodology and B-12 by enzyme immunoassay. Main outcome measures Relationship between low maternal vitamin B-12 levels and total homocysteine and folate levels in pregnant women and newborn babies. Results There was a significant correlation between maternal and neonatal B-12 levels, but not between maternal B-12 and neonatal red blood cell (RBC) folate. There was a weak correlation between maternal B-12 levels and neonatal serum folate. However, there were significant correlations between maternal and neonatal total homocysteine levels and between neonatal B-12 and neonatal total homocysteine levels. Mean (+/-SD) umbilical cord blood B-12, RBC folate, serum folate and total homocysteine levels were 1.7 +/- 0.8, 1.8 +/- 0.8, 2.2 +/- 0.8 and 0.9 +/- 0.3 times higher than maternal B-12, RBC folate, serum folate and total homocysteine values, respectively. Conclusions These data suggest that pregnant women with low B-12 levels are unable to provide the necessary amount of B-12 to their fetuses. The clinical consequences could be the presence of neurological abnormalities as well as the lack of utilisation of homocysteine for methionine transformation.