OBJECTIVE: Adequate maternal red blood cell (RBC) folate levels are recommended to reduce the risk of neural tube birth defects. An analysis of the 2005-2006 National Health and Nutrition Examination Survey (NHANES) data was conducted to determine age- and race-specific RBC folate levels for women of childbearing age (14-45) in the United States (US).
DESIGN: This study was a cross-sectional analysis of the 2005-2006 NHANES data. NHANES is a nationally representative periodic survey that gathers data from laboratory tests (including RBC folate levels), physical examinations, and questionnaires.
MATERIALS AND METHODS: The 2005-2006 NHANES contained data on 10,122 individuals. After excluding men, women not of childbearing age, and women with missing folate data, the final sample included 1,710 participants. Among these, RBC folate levels were assessed across various strata (i.e., age groups 14-25, 26-35, 36-45, racial categories, use of folic acid-containing supplements [FACS]). Sampling weights allowed for creation of nationally representative estimates.
RESULTS: We estimated that US women of childbearing age had a median RBC folate level of 241.0 ng/mL (545.9 nmol/L); 28.8% had evidence of FACS use. Women using FACS had a median RBC folate level of 274.0 ng/mL (620.6 nmol/L) compared with 228.0 ng/mL (516.4 nmol/L) for those not using FACS. Black women had the lowest median RBC folate level, followed by Hispanics, while white woman had the highest. Median RBC folate levels increased across age groups.
CONCLUSION: Median RBC folate levels increase with FACS use and are highest among white women. Increased RBC folate levels have been shown to reduce neural tube defects; thus, a targeted approach to raising RBC folate levels among women of child bearing age may reduce the risk of neural tube defects.
