RESUMO
<p><b>OBJECTIVE</b>To compare plasma and red blood cell folate levels among women in their first trimester of pregnancy from rural areas with high or low prevalence of neural tube defects.</p><p><b>METHODS</b>A cross-sectional study was performed, among women in their first trimester of pregnancy from rural areas with high or low prevalence of neural tube defects in 2003. Non-fasting blood sample were collected and analyzed for plasma and red blood cell folate concentrations for 688 women.</p><p><b>RESULTS</b>The median plasma (10.53 nmol/L) and red blood cell folate (389.2 nmol/L) among women from the high prevalence rural area were lower than those of women from the low prevalence rural area (plasma folate: 30.39 nmol/L, red blood cell level folate: 926.0 nmol/L). Among women from the high prevalence area, about 50% and 43% were respectively, deficient for plasma and red blood cell folate, compared with 6% and 4% respectively, for women from the low prevalence area. The median plasma folate levels among women who took periconceptional folic acid supplements in both high and low prevalence areas were about twice higher than those who did not take the folic acid. The median red blood cell folate level of the folic acid users was 40% higher than those of the non-users. Among those who took folic acid, women in the low prevalence area had 70%-90% higher plasma folate concentration and twice higher red cell folate concentration than women in the high prevalence area.</p><p><b>CONCLUSION</b>Women from the rural area with a high prevalence of neural tube defects had low plasma and red blood cell folate levels. Periconceptional supplementation with folic acid could substantially improve folate status of reproductive-aged women. However, supplementation with 0.4 mg of folic acid per day might be inadequate for women in the high prevalence rural area.</p>