Health Education Research, Vol. 14, No. 3, 327-338,
June 1999
© 1999 Oxford University Press
Understanding the intention to permanently follow a high folate diet among a sample of low-income pregnant women according to the Health Belief Model
Maternal and Child Health Nutrition Department, Grady Health System, Atlanta, GA 30335-3801 and
1 Rollins School of Public Health of Emory University, Atlanta, GA 30322, USA
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Abstract |
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Despite folate fortification of the US food supply beginning January 1, 1998, evidence indicates that a substantial proportion of women of child-bearing age will continue to have folate intakes inadequate for the prevention of neural tube defects (NTDs). Therefore, health education remains an essential component of this public health campaign. The purpose of this study was to determine the applicability of the Health Belief Model (HBM) to understanding the intention to permanently follow a high folate diet among low-income pregnant women. A convenience sample of 251 low-income pregnant women participated in individual 15 min interviews assessing their folate attitudes and beliefs according to the model. Correlations consistent with the HBM were found between the perceived susceptibility, perceived severity, perceived benefits, perceived barriers, self-efficacy and cues to action constructs, and participants' intention to permanently follow a high folate diet (folate intention). In regression analyses, the perceived benefits construct was consistently the most predictive of folate intention. Participants were generally unfamiliar with and had many misperceptions concerning both folate and NTDs. The HBM may offer an effective foundation for development of tailored educational interventions promoting permanent consumption of a high folate diet among low-income women.
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Introduction |
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Folate and neural tube defects (NTDs)
Maternal nutritional status has a significant impact upon pregnancy outcome (Worthington-Roberts and Williams, 1993
). Preparations for a healthy pregnancy must begin during the preconceptional period and very early in pregnancy, before most women know they are pregnant. One example of this is the protective effect of folate against NTDs, which is only effective when women consume adequate folate during the periconceptional period.
Approximately 2500–3000 infants with NTDs (spina bifida, anencephaly and encephalocele) are born annually in the US and another 1500 with these birth defects are aborted or stillborn (Institute of Medicine, 1990; Centers for Disease Control, 1992; Hine, 1996). On a worldwide basis, NTDs affect an estimated 300 000–400 000 births per year (Institute of Medicine, 1990). The social, monetary and emotional costs of these birth defects are devastating.
Research indicates that consumption of at least 400 µg of folate daily during the periconceptional period (approximately 1–3 months prior to conception through the early gestational period) significantly reduces the incidence of NTDs, even among women who have previously delivered affected infants (MRC Vitamin Study Research Group, 1991; Bailey, 1992; Centers for Disease Control, 1992; Czeizel and Dudás, 1992; Romano et al., 1995; Hine, 1996). Folate (folic acid) is a B-vitamin essential for tissue growth and normal metabolic functioning. The Recommended Dietary Allowance for folate during pregnancy is 400 µg/day (National Research Council, 1989). However, researchers estimate that the mean folate intake of women in the US is only 207 µg/day (Subar et al., 1989). Approximately 10% of the population has low folate stores with the highest prevalence documented among women ages 20–40, smokers and non-users of vitamin/mineral supplements (National Research Council, 1989; Institute of Medicine, 1990; Bailey, 1992). Some evidence also suggests that inadequate folate intake is particularly common among low-income and African-American women (Subar et al., 1989; Institute of Medicine, 1990).
In 1995 a new Healthy People 2000 objective (#14.17) was added to monitor the incidence of NTDs and promote their prevention through adequate folate consumption (USDHHS, 1995; National Center for Health Statistics, 1996). Despite recent folate awareness campaigns and media attention concerning folate, researchers know little about women's folate knowledge, attitudes and behaviors (Johnston and Staples, 1997; Sayers et al., 1997; Centers for Disease Control, 1998). A 1997 national survey by the March of Dimes found generally low folate awareness levels and limited use of folate-containing vitamin supplements among women of child-bearing age in the US (Johnston and Staples, 1997).
The Food and Drug Administration issued regulations during 1996 mandating folate fortification of the US food supply (140 µg folate per 100 g flour) by January 1, 1998, to increase the folate intake of women of child-bearing age (Hine, 1996). Research estimates that folate fortification of grain products will result in a net economic benefit to society of nearly $100 million annually by averting costly birth defects (Romano et al., 1995). However, several studies indicate that fortification at the designated level will be inadequate, leaving a substantial proportion of women in the target population below the 400 µg/day folate goal (Crane et al., 1995; Romano et al., 1995; Brown et al., 1997; Daly et al., 1997). For example, one study suggests that the mean folate intake among women of child-bearing age will increase to only 286 µg/day (Brown et al., 1997). Other research proposes that fortification will result in an average increase in folate intake of 100 µg/day, causing an estimated 22% reduction in NTD incidence (Daly et al., 1997; Gregory, 1997). While a 22% reduction is substantial, approximately 50–70% of NTDs may be preventable by folate, leaving many women at risk (Daly et al., 1997). Women continuing to have suboptimal folate intakes will need to obtain the difference through better food selection and/or supplements. Therefore, educational interventions remain essential to help prevent NTDs.
The Health Belief Model (HBM)
The HBM is one of the most widely used public health theoretical frameworks. It can explain health behavior modifications and can function as the foundation for health education interventions (Strecher and Rosenstock, 1997). Social psychologists developed the HBM during the 1950s to predict why individuals did not participate in preventive health behaviors such as immunizations (Rosenstock, 1974). The model assumes a value expectancy approach, postulating that behavior depends upon the expected outcomes of an action and the value an individual places on those outcomes (Shillitoe and Christie, 1989; Strecher and Rosenstock, 1997).
The HBM has six constructs: perceived susceptibility, perceived severity, perceived benefits, perceived barriers, self-efficacy and cues to action (Strecher and Rosenstock, 1997). Researchers have successfully applied the model's constructs to explaining a variety of preventive health behaviors, sick-role behaviors and clinic utilization behaviors [see, e.g. (Rosenstock, 1974; Janz and Becker, 1984; Shillitoe and Christie, 1989)]. However, to date, the model has not been applied to predicting folate consumption for the prevention of NTDs.
The purpose of this study was to test the utility of the HBM in understanding and predicting the intention to permanently follow a high folate diet among low-income pregnant women. Study objectives included: (1) determine the feasibility of using the HBM with folate, and (2) identify focal points for educating low-income women about folate and NTDs.
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Method |
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Research participants
The study was conducted in the Grady Health System (Atlanta, GA), serving primarily minority, indigent clients. The population sampled was low-income pregnant women enrolled on, or eligible for and waiting to enroll on, the Special Supplemental Nutrition Program for Women, Infants and Children (WIC). Cross-sectional convenience sampling was the selection method used.
Study procedures
The study involved a 15 min interview concerning participants' folate beliefs according to the HBM. The principal investigator (A. K.) developed the 58-item interview script. Interviews included items assessing supplement usage, pregnancy-related behaviors, folate knowledge, intention to permanently follow a high folate diet, the six HBM constructs, typical intake of enriched grain products and demographics. The authors examine the HBM herein, while the remaining folate issues are analyzed in another publication (Kloeblen, 1999).
Participants were recruited as volunteers while they waited to enroll on the WIC Program, to pick up WIC vouchers or to attend prenatal care appointments. The study excluded women not enrolled on WIC, women eligible for WIC but not waiting to enroll the day of the interview and women who did not speak English. All participants provided written informed consent.
Interviews were conducted by the authors. Prior to the HBM assessment section, interviewers told participants the following: `Folic acid is a vitamin found in some foods. You may not know everything about folic acid, but please answer the statements as best as you can based on what you personally feel or believe.'. Upon interview completion, interviewers educated participants about folate and NTDs and provided them with rewards for their participation. Data analyses were conducted using the Epi Info statistical software package (Centers for Disease Control and Prevention, 1994, version 6.02, Atlanta, GA). The Emory University School of Medicine Human Investigations Committee, and the Grady Research and Publications Committee approved all study procedures.
Variables
All variables were measured by self-report. Construct scores excluded records with missing responses. HBM constructs were measured using five-point Likert scales (strongly agree = 5 through strongly disagree = 1). Intention to permanently follow a high folate diet (folate intention) was measured by summing participants' responses to a statement mentioned twice during each interview, `I plan to follow a diet high in folic acid all of the time, even when I am not pregnant'. A higher total score (range: 2–10) reflects greater intention to follow a high folate diet at all times. The perceived susceptibility construct (range: 5–25) was measured by summing participants' responses to five statements, with a higher score reflecting higher perceived risk for having a baby with a birth defect or having pregnancy complications. The perceived severity construct (range: 5–25) was measured similarly, with a higher score representing greater perceived seriousness of NTDs. Refer to Table I for the mean scores, percent distribution of participants' responses to and correlations with folate intention of the statements comprising the perceived susceptibility and perceived severity constructs.
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The perceived benefits construct (range: 6–30) was measured by summing participants' responses to six statements, with a higher score reflecting more perceived advantages to permanently following a high folate diet. The perceived barriers construct (range: 6–30) was measured in the same manner, with a higher score indicating greater perceived costs to permanently following a high folate diet. Refer to Table II
for the mean scores, percent distribution of participants' responses to and correlations with folate intention of the statements representing the perceived benefits and perceived barriers constructs.
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The Health Belief Model total score (range: 22–110) was measured by summing participants' responses to statements comprising the perceived susceptibility, perceived severity, perceived benefits and perceived barriers constructs. Scores from statements representing the perceived barriers construct were reversed (changed to strongly agree = 1 through strongly disagree = 5). A higher Health Belief Model total score reflects greater support from the model for a subject's likelihood of intending to permanently follow a high folate diet, the recommended preventive health action. For the purpose of correlations between the Health Belief Model total score and other study variables, the totals of the four HBM constructs that constitute the score were each converted to a scale of 0–100 to account for variations in how the four constructs were measured (i.e. possible range of 5–25 versus 6–30).
The self-efficacy construct (range: 2–10) was measured by summing participants' responses to two statements, with a higher score representing greater confidence in one's ability to permanently follow a high folate diet. The cues to action [internal or external factors that trigger action (Strecher and Rosenstock, 1997)] were each measured individually, some on five-point Likert scales and some as yes/no questions. Refer to Table III for the mean scores, percent distribution of participants' responses to and correlations with folate intention of the statements used to represent the self-efficacy and cues to action constructs.
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Results |
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Sample characteristics
The authors conducted interviews with 251 women from March through May 1997. The response rate was 96.2%. Refer to Table IV
for the distribution of sample characteristics.
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HBM
Perceived susceptibility, perceived severity, perceived benefits, self-efficacy and the HBM total score were positively correlated with folate intention. The perceived barriers construct was negatively correlated with folate intention. The actual range of participants' folate intention scores was 3–10 with a mean score (mean ± SD) of 6.9 ± 1.5 (n = 248). Refer to Table V
for a summary of the results for the HBM constructs and their correlations with folate intention.
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Having ever talked about folate with anyone was correlated with the following HBM constructs: perceived benefits (r = 0.25, P < 0.01), perceived barriers (r = –0.41, P < 0.01), Health Belief Model total score (r = 0.27, P < 0.01) and self-efficacy (r = 0.26, P < 0.01). Results demonstrated no correlation between knowing someone who had or lost a baby with a NTD and any of the HBM constructs. Only one subject had ever had a baby with a NTD; therefore, further analyses excluded this variable. The self-efficacy construct was positively correlated with the Health Belief Model total score variable (r = 0.59, F[1,246] = 129.33, P < 0.01) and was significantly correlated with the other HBM constructs.
Refer to Table VI for correlations between the demographics and HBM constructs. No correlations were found between the HBM constructs and parity or maternal ethnicity. Maternal gestational age at prenatal care onset was only correlated with the perceived barriers construct (r = 0.13, F[1,244] = 4.40, P < 0.05).
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Standard multiple linear regression analyses were conducted for predicting folate intention from the HBM constructs and demographics. The regression models report the multiple correlation (R), squared multiple correlation (R2), F-test and significance level. Due to variations in how the five HBM constructs were measured, standardized regression coefficients are reported. Analyses omitted the cues to action since most cues did not significantly contribute to the regression models and several represented preferred learning methods (e.g. reading, watching television, talking with someone) rather than pertinent factors influencing folate intention. Refer to Table VII
for the regression model predicting folate intention from five HBM constructs (R = 0.67, R2 = 0.45, F[5,242] = 39.93, P < 0.01). The perceived benefits construct (sr2 = 0.09) was the strongest predictor in the regression. Unique variance contributed by the constructs totaled 13% (0.13), while shared variability totaled 32% (0.32), resulting in the model explaining 45% of the variance in the intention to permanently follow a high folate diet. The perceived susceptibility and perceived severity constructs were not significant predictors of folate intention.
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When the six demographic variables were added to the model, only maternal age (sr2 = 0.01) and parity (sr2 = 0.01) significantly contributed to the prediction equation beyond the HBM constructs (R = 0.69, R2 = 0.47, F[11,234] = 18.85, P < 0.01). The strongest predictor in the equation remained the perceived benefits construct (sr2 = 0.08).
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Discussion |
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This study establishes preliminary confirmation of the feasibility of applying the HBM to predicting and understanding the intention to permanently follow a high folate diet among low-income pregnant women for the prevention of NTDs. Findings demonstrated correlations consistent with the HBM framework between the model's constructs and the intention to permanently follow a high folate diet. Perceived benefits was the most predictive of folate intention. However, over 50% of the variance in folate intention remains unexplained by the study variables.
Using public health theories and models to help understand, describe and organize a public health issue such as folate consumption into a comprehensive, effective system of information has many benefits. Theories can provide a foundation from which to better understand a target population's folate attitudes, behaviors and educational needs. Theories can serve as a guide for folate educational research to help identify modifiable factors influencing the intention to permanently follow a high folate diet. Theories and models also traditionally incorporate methods for influencing the behavior examined. Thus, using a theoretical approach has the potential to enhance folate educational strategy development. Beyond this single application of theory to folate, future use of other health behavior change frameworks such as Social Learning Theory (Rosenstock et al., 1988), the Transtheoretical Model (Prochaska et al., 1992) and the Theory of Reasoned Action (Ajzen and Fishbein, 1980) may be instrumental in identifying how to not only motivate but influence individual change as well as environmental support for increased folate intakes among women.
Practitioners can use the HBM to tailor folate educational campaigns to this low-income and likely other populations by using the model to guide examination of the population's folate attitudes, behaviors and beliefs, and detect appropriate educational techniques. The model identifies both specific areas to target for education (i.e. the perceived susceptibility, perceived severity, perceived benefits, perceived barriers and self-efficacy constructs) and useful educational approaches (i.e. the cues to action). Using the HBM to focus a folate campaign and provide educational messages relevant to the target audience is more likely to increase the population's intention to follow the diet. Thus, the HBM can be a practical tool to help educators develop effective folate intervention strategies tailored to the target population's needs.
Study findings identified several basic educational needs for this population. Most participants generally appeared unfamiliar with folate and NTDs. Over 70% of participants believed they did not know enough about what foods are high in folate. Over 70% of these pregnant women had also never spoken with anyone before about folate. Moreover, many women had basic misperceptions concerning folate, NTDs, pregnancy issues and their risk for pregnancy complications. Increasing this population's awareness of the need for folate through educational campaigns is likely to improve the population's intention to permanently follow a high folate diet (Johnston and Staples, 1997; Sayers et al., 1997). Campaigns should focus on promoting the benefits of following a high folate diet while dispelling folate misperceptions and barriers. For example, one common misperception perpetuated by several health organizations promoting folate consumption is that following a high folate diet is difficult, expensive, time-consuming and less effective than vitamin supplementation. However, with folate fortification of the food supply and by complying with national nutrition guidelines such as the Food Guide Pyramid recommendations, following a high folate diet can be easy, inexpensive and can achieve red blood cell folate levels effective for the prevention of NTDs (Cuskelly et al., 1996; Hine, 1996; Brown et al., 1997; Daly et al., 1997; Firth et al., 1998).
Although this study offers a new approach to understanding folate intention, attitudes and beliefs, there are several limitations to its findings. The sample was not randomly selected and no reliability or validity data were collected on the instrument, limiting the generalizability and interpretation of the results. More rigorous research is warranted to confirm these findings, and to develop a reliable, valid instrument for accurate identification and measurement of the model's constructs regarding folate and NTD prevention.
The association between the intention to follow a high folate diet and actual folate dietary behavior remains untested and requires investigation. Furthermore, how well the HBM constructs predict actual folate intake needs examination. Another publication addresses both of the aforementioned issues in relationship to participants' estimated daily folate intake from grain products (Kloeblen, 1999). Although the literature documents positive correlations between certain behavioral intentions and actual health behaviors [see, e.g. (Manstead et al., 1983; Kessler et al., 1995)], information regarding the relationship between dietary intention and actual behavior remains limited and equivocal [see, e.g. (Becker et al., 1977; Shepherd and Stockley, 1987; Tuorila, 1987; Conner, 1993)]. This may be partially due to the difficulty of incorporating factors into research such as the context in which people purchase, prepare and consume food, which is crucial for understanding dietary behaviors. Contextual influences such as these concerning diet choices may attenuate the predictive utility of a dietary intention, including the intention to follow a high folate diet, since it is impossible for research to control for the myriad of different situations in which people make dietary decisions.
The HBM may not have been the most appropriate theoretical framework for use with this population since folate knowledge among participants appeared low. Participants' intentions and beliefs may not be very meaningful if they do not fully understand what following a high folate diet entails. Therefore, social desirability could have substantially influenced participants' responses, most notably among women with limited folate knowledge. Interviewers did not provide more background folate information to participants because the study also assessed participants' actual folate knowledge and the authors wanted to avoid influencing participants' responses to those knowledge-based statements (Kloeblen, 1999). Perhaps a more appropriate procedure in the future would be to: (1) first assess participants' folate knowledge, (2) then provide participants with detailed, accurate folate information and (3) assess the HBM model constructs last. Participants could then provide more informed responses to the HBM construct statements while preserving the integrity of their basic folate knowledge answers.
Although this study focused specifically on folate-related diet issues in response to the new US folate fortification regulations and to the recently established link between folate and NTDs, the advisability of dedicating scarce public health resources to designing health education campaigns that address single nutrients such as folate is questionable. People do not tend to make food choices in a vacuum, based upon their knowledge of specific nutrients. Promoting consumption of an overall healthy diet for women may be a more effective approach. For example, campaigns in the US could encourage women to follow the Food Guide Pyramid dietary recommendations (US DoA, 1992), which can provide adequate folate (400 µg minimum) daily when considering folate fortification of grains; consumption of the minimum number of servings of fruits, vegetables and grains recommended per day; and intake of a relatively balanced, varied diet.
Ultimately, folate fortification of the food supply is only one part of the solution to decreasing the incidence of NTDs. Many women of child-bearing age will remain unprotected against NTDs despite folate fortification of grains (Crane et al., 1995; Romano et al., 1995; Brown et al., 1997; Daly et al., 1997). Educational interventions continue to be essential to fill in the gap for those women who will still have suboptimal folate intakes. However, traditional educational strategies that provide only general information to all women, disregarding the folate-related attitudes of the segment of the target audience being served, will likely be ineffective in changing behaviors. Using public health theories to tailor interventions to the target population can overcome this problem. The HBM has potential for providing the foundation to folate educational interventions at the individual and community level targeting low-income women of child-bearing age. Using this model may offer educators a valuable opportunity to more effectively promote the adoption of a high folate diet among low-income women through tailored educational interventions, thus improving perinatal outcomes.
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References |
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TopAbstractIntroductionMethodResultsDiscussionReferences |
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Ajzen, I. and Fishbein, M. (1980) Understanding Attitudes and Predicting Social Behavior. Prentice-Hall, Englewood Cliffs, NJ.
Bailey, L. B. (1992) Evaluation of a new recommended dietary allowance for folate. Journal of the American Dietetic Association, 92, 463–468, 471.[Web of Science][Medline]
Becker, M. H., Maiman, L. A., Kirscht, J. P., Haefner, D. P. and Drachman, R. H. (1977) The health belief model and prediction of dietary compliance: a field experiment. Journal of Health and Social Behavior, 18, 348–366.[Web of Science][Medline]
Brown, J. E., Jacobs, D. R., Hartman, T. J., Barosso, G. M., Stang, J. S., Gross, M. D. and Zeuske, M. A. (1997) Predictors of red cell folate level in women attempting pregnancy. Journal of the American Medical Association, 277, 548–552.
Centers for Disease Control (1992) Recommendations for the use of folic acid to reduce the number of cases of spina bifida and other neural tube defects. Morbidity and Mortality Weekly Report, 41, 1–7.
Centers for Disease Control (1998) Use of folic acid-containing supplements among women of childbearing age—United States, 1997. Morbidity and Mortality Weekly Report, 47, 131–134.
Conner, M. T. (1993) Individualized measurement of attitudes towards foods. Appetite, 20, 235–238.[Web of Science][Medline]
Crane, N. T., Wilson, D. B., Cook, A., Lewis, C. J., Yetley, E. A. and Rader, J. I. (1995) Evaluating food fortification options: general principles revisited with folic acid. American Journal of Public Health, 85, 660–666.
Cuskelly, G. J., McNulty, H. and Scott, J. M. (1996) Effect of increasing dietary folate on red-cell folate: implications for prevention of neural tube defects. Lancet, 347, 657–659.[Web of Science][Medline]
Czeizel, A. E. and Dudás, I. (1992) Prevention of the first occurrence of neural-tube defects by periconceptional vitamin supplementation. New England Journal of Medicine, 327, 1832–1835.[Abstract]
Daly, S., Mills, J. L., Molloy, A. M., Conley, M., Lee, Y. J., Kirke, P. N., Weir, D. G. and Scott, J. M. (1997) Minimum effective dose of folic acid for food fortification to prevent neural-tube defects. Lancet, 350, 1666–1669.[Web of Science][Medline]
Firth, Y., Murtaugh, M. A. and Tangney, C. C. (1998) Estimation of individual intakes of folate in women of childbearing age with and without simulation of folic acid fortifications. Journal of the American Dietetic Association, 98, 985–988.[Web of Science][Medline]
Gregory, J. F. III. (1997) Bioavailability of folate. European Journal of Clinical Nutrition, 51 (Suppl.), 554–559.[Web of Science][Medline]
Hine, R. J. (1996) What practitioners need to know about folic acid. Journal of the American Dietetic Association, 96, 451–452.[Web of Science][Medline]
Institute of Medicine (1990) Nutrition During Pregnancy: Weight Gain, Nutrient Supplements. National Academy Press, Washington, DC.
Janz, N. K. and Becker, M. H. (1984) The health belief model: a decade later. Health Education Quarterly, 11, 1–47.[Web of Science][Medline]
Johnston, R. B. and Staples, D. A. (1997) Knowledge and use of folic acid by women of childbearing age—United States, 1997. Morbidity and Mortality Weekly Report, 46, 721–723.
Kessler, L. A., Gielen, A. C., Diener-West, M. and Paige, D. M. (1995) The effect of a woman's significant other on her breastfeeding decision. Journal of Human Lactation, 11, 103–109.
Kloeblen, A. S. (1999) Folate knowledge, intake from fortified grain products, and periconceptional supplementation patterns of a sample of low-income pregnant women according to the health belief model. Journal of the American Dietetic Association, 99, 33–38.[Web of Science][Medline]
Manstead, A. S. R., Proffitt, C. and Smart, J. L. (1983) Predicting and understanding mothers' infant-feeding intentions and behavior: testing the theory of reasoned action. Journal of Personality and Social Psychology, 44, 657–671.[Web of Science][Medline]
MRC Vitamin Study Research Group (1991) Prevention of neural tube defects: results of the medical research council vitamin study. Lancet, 338, 131–137.[Web of Science][Medline]
National Research Council (1989) Recommended Dietary Allowances, 10th edn. National Academy Press, Washington, DC.
National Center for Health Statistics (1996) Healthy People 2000 Review, 1995–96. DHHS publ. no. (PHS) 96-1256. Public Health Service Hyattsville, MD.
Prochaska, J. O., DiClemente, C. C. and Norcross, J. C. (1992) In search of how people change: applications to addictive behaviors. American Psychologist, 47, 1102–1114.[Medline]
Romano, P. S., Waitzman, N. J., Scheffer, R. M. and Pi, R. D. (1995) Folic acid fortification of grain: an economic analysis. American Journal of Public Health, 85, 667–676.
Rosenstock, I. M. (1974) Historical origins of the health belief model. Health Education Monographs, 2, 328–335.[Web of Science]
Rosenstock, I. M., Strecher, V. J. and Becker, M. H. (1988) Social learning theory and the health belief model. Health Education Quarterly, 15, 175–183.[Web of Science][Medline]
Sayers, G. M., Hughes, N., Scallan, E. and Johnson, Z. (1997) A survey of knowledge and use of folic acid among women of child-bearing age in Dublin. Journal of Public Health Medicine, 19, 328–332.
Shepherd, R. and Stockley, L. (1987) Nutrition knowledge, attitudes, and fat consumption. Journal of the American Dietetic Association, 87, 615–619.[Web of Science][Medline]
Shillitoe, R. W. and Christie, M. J. (1989) Determinants of self-care: the health belief model. Holistic Medicine, 4, 3–17.
Strecher, V. J. and Rosenstock, I. M. (1997). The health belief model. In Glanz, K., Lewis, F. M. and Rimer, B. K. (eds), Health Behavior and Health Education: Theory, Research and Practice, 2nd edn. Jossey-Bass, San Francisco, CA, pp. 41–59.
Subar, A. F., Block, G. and James, L. D. (1989) Folate intake and food sources in the US population. American Journal of Clinical Nutrition, 50, 508–516.
Tuorila, H. (1987) Selection of milks with varying fat contents and related overall liking, attitudes, norms and intentions. Appetite, 8, 1–14.[Web of Science][Medline]
Worthington-Roberts, B. and Williams, S. R. (1993) Nutrition in Pregnancy and Lactation, 5th edn. Mosby-Year Book, St Louis, MO.
US Department of Agriculture, Human Nutrition Information Service (1992) The Food Guide Pyramid [Brochure]. Home and Garden Bulletin 252. US DoA, Washington, DC.
US Department of Health and Human Services, Public Health Service (1995) Healthy People 2000: Midcourse Review and 1995 Revisions. US Government Printing Office, Washington, DC.
Received on August 5, 1997; accepted on March 24, 1998
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