Modern methods of NFP have been shown to be highly effective with method effectiveness figures ranging from 97-99.9 percent. Use effectiveness, reflecting the actual experience in day-to-day life, shows 90-99 percent effectiveness. To achieve these effectiveness figures, it is important that couples participate in a structured learning program with individualized follow-up, that they chart consistently and correctly, and that they follow all rules, especially complete genital abstinence during the method-defined fertile time.