Relationship between dietary folate intakes, maternal plasma total homocysteine and B-vitamins during pregnancy and fetal growth in Japan.

Background: Adequate folate status in pregnancy is important for satisfactory pregnancy outcome.

Aim Of The Study: The objective of the present study was to evaluate folate status in healthy pregnant women by assessing dietary folate intakes and measuring changes in folate-related biomarkers including plasma tHcy, serum vitamin B(12) (B(12)), and serum and RBC folate concentrations in each trimester and to examine their relation to fetal growth.

Methods: From 94 pregnant women, 3-day-dietary records were obtained and blood was collected for plasma total homocysteine (tHcy), serum B(12), and serum and red-blood cell (RBC) folate measurements. Infant anthropometric measurements were made immediately after birth.

Results: Average folate intake was less than 300 microg/day with a mean energy intake of about 1800 kcal. Mean serum and RBC folate concentrations declined significantly during gestation (p < 0.05). Mean serum B(12) also significantly decreased (p < 0.01), whereas plasma tHcy increased from 5.1 in the first trimester to 5.9 micromol/l in the third trimester (p < 0.01). Multiple regression analyses, after controlling for maternal age, parity and pre-pregnancy body-mass index indicated that a 1.0 micromol/l increase in plasma tHcy in the third trimester corresponded to a 151 g decrease in birth weight (p < 0.01). Neither B(12) nor folate concentrations in all three trimesters showed any significant associations with birthweight. Plasma pyridoxal-5'-phosphate concentrations were markedly low, and were consistent with low intake of vitamin B(6) in our population.

Conclusion: Our data suggest that higher plasma tHcy in the third trimester is a predictor of lower birth weight. In general, the dietary intake of B-vitamins and energy may be inadequate in our population, suggesting intervention is necessary.