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.