Folate and vitamin B12 status of women in Newfoundland at their first prenatal visit

Newfoundland has one of the highest rates of neural tube defects in North America. Given the association between low maternal folic acid levels and neural tube defects, a cross-sectional study was conducted to obtain base-line data on the folate and vitamin B12 status of a sample of women in Newfoundland who were pregnant.

Blood samples were collected between August 1996 and July 1997 from 1424 pregnant women in Newfoundland during the first prenatal visit (at approximately 16 weeks' gestation); this represented approximately 25% of the women in Newfoundland who were pregnant during this period. The samples were analysed for serum folate, vitamin B12, red blood cell folate and homocysteine.

Median values for serum folate, red blood cell folate and serum vitamin B12 were 25 nmol/L, 650 nmol/L and 180 pmol/L, respectively. On the basis of the interpretive criteria used for red blood cell folate status, 157 (11.0%) of the 1424 women were deficient (< 340 nmol/L) and a further 180 (12.6%) were classified as indeterminate (340-420 nmol/L). Serum homocysteine levels, measured in subsets of the red blood cell folate status groups, supported the inadequate folate status. Serum vitamin B12 levels of 621 (43.6%) women were classified as deficient or marginal; however, the validity of the interpretive criteria for pregnant women is questionable.

A large proportion of pregnant women surveyed in Newfoundland in 1997 had low red blood cell folate levels.