Relationship between total homocysteine and folate levels in pregnant women and their newborn babies according to maternal serum levels of vitamin B 12

Abstract

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, São 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 perfomance liquid chromatography, folate by ion capture methodology and B 12 by enzyme immunoassay. Main outcome measures Relationship between low maternal vitamin B12 levels and total homocysteine and folate levels in pregnant women and new born 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.