Influence of motivation on the efficacy of natural family planning.

PURPOSE To determine the influence of mutual motivation on unintended pregnancy rates of couples who used natural family planning (NFP) methods to avoid pregnancy. STUDY DESIGN AND METHODS Using an online taught NFP method, 358 women and (their male partners) indicated "how much" and "how hard" they wished to avoid pregnancy on a scale of 0 to 10 before each menstrual cycle charted over 12 month of use. This motivation scale is used in the National Survey of Family Growth as a measure of motivation. All pregnancies were verified with an online pregnancy evaluation and urine-based pregnancy test. A combined motivation score was used in analysis. RESULTS There were 28 pregnancies among the low-motivation participants (N = 60) and 16 among the high-motivation participants (N = 298). At 12 months of use, there were 75 pregnancies per 100 users for the low-motivation group and only 8 for the high-motivation group. There was an 80% greater likelihood of a pregnancy with the low-motivation group (χ = 25.5, p < .001, odds ratio = 1.80; 95% confidence interval = 1.61-1.90). CLINICAL IMPLICATIONS High motivation to avoid pregnancy by both the female user of a behavioral method of family planning and her male partner is required for high efficacy. Assessing motivation of both the woman and her male partner before prescribing NFP methods is recommended.