Comparison of blood folate levels among pregnant Chinese women in areas with high and low prevalence of neural tube defects.

OBJECTIVE To characterise plasma and red-blood-cell (RBC) folate status among pregnant women in an area with an extremely high prevalence of neural tube defects, and to compare them with those of women from a low prevalence area. DESIGN A cross-sectional survey conducted in 2003. SETTING One county and one city from each of the high prevalence area and the low prevalence area in China. SUBJECTS Five hundred and sixty-two women in their first trimester of pregnancy in the high prevalence area and 695 pregnant women in the low prevalence area. RESULTS Women in the high prevalence area had less than half the plasma and RBC folate concentrations (12.2 and 440.0 nmol l- 1, respectively) of women in the low prevalence area (33.5 and 910.4 nmol l- 1, respectively). In the high prevalence area, 40% of rural women were deficient in RBC folate and 50% were deficient in plasma folate; 20% of urban women were deficient in RBC folate and 30% deficient in plasma folate. In contrast, only 4% (RBC folate) and 6% (plasma folate) of rural women, and 2% (RBC folate) and 1% (plasma folate) of urban women, were folate-deficient in the low prevalence area. Less than 10% of rural and about 26% of urban women in the high prevalence area took folic acid periconceptionally, compared with 70% and 60% of women in the low prevalence area. CONCLUSIONS Blood folate deficiency is highly prevalent among pregnant women in an area of China with a very high prevalence of neural tube defects.