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 B12 (B12) levels, and to analyse the impact of maternal B12 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 B12 by enzyme immunoassay.

Main Outcome Measures: Relationship between low maternal vitamin B12 levels and total homocysteine and folate levels in pregnant women and newborn babies.

Results: There was a significant correlation between maternal and neonatal B12 levels, but not between maternal B12 and neonatal red blood cell (RBC) folate. There was a weak correlation between maternal B12 levels and neonatal serum folate. However, there were significant correlations between maternal and neonatal total homocysteine levels and between neonatal B12 and neonatal total homocysteine levels. Mean (+/- SD) umbilical cord blood B12, 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 B12, RBC folate, serum folate and total homocysteine values, respectively.

Conclusions: These data suggest that pregnant women with low B12 levels are unable to provide the necessary amount of B12 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.