NATURAL FAMILY-PLANNING WITH AND WITHOUT BARRIER METHOD USE IN THE FERTILE PHASE - EFFICACY IN RELATION TO SEXUAL-BEHAVIOR - A GERMAN PROSPECTIVE LONG-TERM STUDY

A large prospective long-term study with users of natural family plann ing (NFP) methods has been conducted to analyze the relation between u nintended pregnancy rates and sexual behavior with special reference t o barrier method use in the fertile phase. Seven hundred and fifty eig ht NFP beginners, 19-45 years of age, 14 870 cycles, 28 unintended pre gnancies were studied. Of the couples, 54.2% use NFP only or predomina ntly and 45.9% use mixed methods (additional barrier method use in the fertile phase in 55.7% of the cycles). The overall pregnancy rate aft er 12 cycles of exposure is 2.2% according to the actuarial method. Th ere is no significant difference between NFP users and mixed methods u sers and also no significant effect of duration of use in the first 5 years of exposure. During ''perfect use'' the pregnancy rate at 12 mon ths is 0.63%. When only protected intercourse takes place in the ferti le phase the pregnancy rate is 0.45%. The symptothermal method of NFP is most unforgiving for imperfect use (unprotected intercourse in the fertile phase). However, it is extremely effective when either abstine nce or protected intercourse is used in the fertile phase.