Cumulative pregnancy rates in patients with apparently normal fertility and fertility-focused intercourse.

Fifty consecutive clients achieved pregnancy using a standardization modification of the Billings ovulation method (the Creighton Model Natural Family Planning System). Of 50 clients followed, 38 (76%) achieved pregnancy in the first cycle of fertility-focused intercourse, 45 of 50 (90%) achieved pregnancy by the third cycle and 49 of 50 achieved pregnancy by the sixth cycle (98%).