Use of Folic Acid-Containing Supplements Among Women of Childbearing Age -- United States, 1997

Each year in the United States, approximately 4000 pregnancies result in spina bifida or anencephaly. Babies born with spina bifida usually survive, often with serious disability, but anencephaly is invariably fatal. The B vitamin folic acid can reduce the occurrence of spina bifida and anencephaly by at least 50% when taken daily before conception and during early pregnancy (1,2). In 1992, the Public Health Service (PHS) recommended that all women of childbearing age who are capable of becoming pregnant consume 400 ug of folic acid daily (3). This report summarizes findings from a survey conducted during January and February 1997 and indicates that only one third of women of childbearing age consume a supplement containing the recommended amount of folic acid daily.

In 1997, the March of Dimes contracted the Gallup Organization to conduct a random-digit-dialed telephone survey of a stratified national sample of 2001 U.S. women aged 18-45 years to assess knowledge about folic acid and use of vitamin supplements (4). The response rate was 50%. Statistical estimates were weighted to reflect the total population of women aged 18-45 years in the contiguous United States who resided in households with telephones. The margin of error for estimates based on the total sample size was plus or minus 2%. The questionnaire and methods used in 1997 were identical to those used in a 1995 survey (5).

Overall, 64.4% of women of childbearing age reported taking some form of vitamin supplement: 44.3% used a folic acid-containing supplement (32.2% daily and 12.1% less than daily), and 20.1% used a supplement that did not contain folic acid (12.5% daily and 7.6% less than daily).

Daily use of a folic acid-containing supplement was 22.8% among women aged less than 25 years, 19.6% among those with less than a high school education, 22.5% among those with household incomes less than $25,000, 26.1% among those who were unmarried, 28.8% among those who had not heard of the PHS recommendation for use of folic acid, and 24.3% among those who were of races other than white (Table_1). Among women who had heard of the PHS recommendation about folic acid, 45.2% reported taking a folic acid-containing supplement daily, compared with 28.8% of women who had not heard about the recommendation.

Among the 12.1% of women who were less-than-daily users of vitamins containing folic acid, 43.4% reported taking vitamins less than once a week; 53.1%, one to four times per week; and 3.2%, five to six times per week. Forgetting to take a vitamin was the main reason for less-than-daily use (49.0%). Among those who did not use any vitamins, 55.8% either felt they did not need them or had "no particular reason" for not taking vitamins, and 14.4% reported that they did not need them because they believed their diets were sufficient.

Overall, 57.8% of women who did not take supplements daily reported that they needed more information about vitamin and mineral supplements. This opinion was more common among Hispanics (71.4%) and women of races other than white (74.6%).

Overall, 59.8% of women who did not take supplements daily reported that cost may be the reason for not taking vitamins (71.9% of women with incomes less than $25,000 per year versus 46.4% with incomes greater than or equal to $50,000). However, 3.8% of women who reported taking any vitamin or mineral supplements indicated that "vitamins cost too much."

Reported by: RB Johnston, Jr, MD, DA Staples, March of Dimes Birth Defects Foundation, White Plains, New York. Birth Defects and Genetic Diseases Br, Div of Birth Defects and Developmental Disabilities, National Center for Environmental Health, CDC.

Editorial Note

Editorial Note: The findings in this report indicate that less than one third (32.2%) of women of childbearing age consume daily a supplement containing folic acid. Among the 67.8% of women who did not take a folic acid-containing supplement daily, approximately half (32.2%) used a supplement but either did not take one daily or took a supplement that did not contain folic acid. Because these women apparently believe they need a supplement and are already taking one, they may be easily persuaded to use a folic acid-containing supplement daily and could especially be targeted in educational and advertising campaigns.

Periconceptional use of multivitamins containing folic acid reduces the risk for neural tube defects and may reduce the risk for other birth defects (6,7). The finding that most women felt they needed more information about supplements underscores the need for more health education about the role of folic acid and multivitamins in preventing birth defects. In addition, the finding that vitamin use was lowest among women in minority groups and among those with the lowest incomes suggests that providing multivitamins at reduced or no cost may enhance the consumption of multivitamins among these women.

The findings in this report are subject to at least one important limitation. The response rate for this telephone survey was low (50%). Knowledge and behavior patterns of nonparticipants may have been different from those of participants.

As of January 1, 1998, the Food and Drug Administration requires that all enriched cereal grains be fortified with folic acid. To obtain the PHS recommended amount of folic acid, women will need to either take a folic acid supplement daily, eat a fortified breakfast cereal containing 100% of the daily value of folic acid, or increase their consumption of foods fortified with folic acid (e.g., cereal, bread, rice, and pasta) and foods naturally rich in folates (e.g., orange juice and green vegetables).

References

1. Medical Research Council Vitamin Study Research Group. Prevention of neural tube defects: results of the Medical Research Council vitamin study. Lancet 1991;338:131-7.

2. Czeizel AE, Dudas I. Prevention of the first occurrence of neural-tube defects by periconceptional vitamin supplementation. N Engl J Med 1992;327:1832-5.

3. CDC. Recommendations for use of folic acid to reduce the number of cases of spina bifida and other neural tube defects. MMWR 1992;41(no. RR-14).

4. CDC. Knowledge and use of folic acid by women of childbearing age -- United States, 1997. MMWR 1997;46:721-3.

5. CDC. Knowledge and use of folic acid by women of childbearing age -- United States, 1995. MMWR 1995;44:716-8.

6. Li DK, Daling JR, Mueller BA, Hickok DE, Fantel AG, Weiss NS. Periconceptional multivitamin use in relation to the risk of congenital urinary tract anomalies. Epidemiology 1995;6:212-8.

7. Botto LD, Khoury MJ, Mulinare J, Erickson JD. Periconceptional multivitamin use and the occurrence of conotruncal heart defects: results from a population-based, case-control study. Pediatrics 1996;98:911-7.

TABLE 1. Percentage of women of childbearing age who reported taking either a folic
acid-containing supplement or a supplement not containing folic acid, by selected
sociodemographic characteristics -- United States, 1997
===================================================================================
                                  Used a vitamin supplement
                           ---------------------------------------
                               Contains folic acid       Does not     Did not use
                            -------------------------     contain      a vitamin
Characteristic              Daily     Less than daily   folic acid    supplement
---------------------------------------------------------------------------------
Age group (yrs)
 18-24                      22.8%           9.6%           23.7%         43.9%
 25-34                      35.5%          13.8%           15.8%         34.9%
 35-45                      34.6%          11.9%           21.2%         32.3%

Education
 Less than high school      19.6%           8.3%           21.1%         51.0%
 High school                29.6%          12.5%           17.8%         40.1%
 College or above           36.7%          12.6%           20.6%         30.1%

Annual household income
        <$25,000            22.5%          11.3%           21.8%         44.4%
 $25,000-$39,999            32.2%          15.0%           18.2%         34.6%
 $40,000-$49,999            41.0%           7.0%           22.4%         29.6%
       >=$50,000            42.9%          10.8%           18.1%         32.4%

Marital status
 Married                    36.7%          12.8%           18.1%         32.4%
 Unmarried                  26.1%          11.2%           22.3%         40.4%

Race
 White                      34.8%          12.7%           19.1%         33.4%
 Other                      24.3%           9.6%           22.2%         43.9%

Ethnicity
 Hispanic                   31.8%           7.1%           21.1%         40.0%
 Non-Hispanic               32.5%          12.5%           19.8%         35.2%

Have children
 Yes                        32.5%          12.8%           19.3%         35.4%
 No                         32.1%          10.7%           21.1%         36.1%

Aware of folic acid
 Yes                        36.3%          12.2%           21.2%         30.3%
 No                         24.8%          11.9%           17.7%         45.6%

Heard folic acid
 recommendation
 Yes                        45.2%          11.3%           18.6%         24.9%
 No                         28.8%          12.3%           20.3%         38.6%

Total                       32.2%          12.1%           20.1%         35.6%
---------------------------------------------------------------------------------
===================================================================================

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