Using theory to guide quantitative formative research: A test of three social influence models

Numerous studies have shown that periconceptional use of folic acid alone or in multivitamins, is effective for reducing the risk of serious birth defects (i.e., neural tube defects—NTDs). The U.S. Public Health Service and Institute of Medicine issued separate recommendations that all women capable of becoming pregnant consume 400 micrograms (µg) of folic acid daily. Since folic acid fortification of the U.S. food supply began in 1998, the prevalence of NTDs has been reduced by 26%. However, even with fortification, most women do not reach the daily recommended level; therefore, increasing the use of vitamins containing folic acid remains an important component of NTD prevention.

Conducting theory-guided research on multivitamin use was essential given the lack of knowledge surrounding this behavior. To this end, this quantitative study tested three social influence and behavior models—the theory of reasoned action, the theory of planned behavior, and social cognitive theory—to determine which theory, or theoretical constructs, best predicted multivitamin use and might be used to guide message design to increase folic acid use. A nationally representative sample of 1,048 women of childbearing age was obtained through data from the 2004 re-contact HealthStyles survey by Porter-Novelli. Results indicated that multivitamin use was best predicted by constructs from the theory of planned behavior and social cognitive theory (e.g., attitude, self-efficacy). The practical and theoretical implications of the results are discussed in light of using these findings to inform further formative research that was part of planning a multivitamin promotion initiative.