The actual effectiveness rates of natural and barrier methods of family planning are lower than the theoretical ones. If couples accurately defined the limits of the fertile phase and used barriers at that time, then actual effectiveness might increase. A randomized, controlled clinical trial was initiated to determine the effectiveness of the contraceptive sponge used only during the fertile time and to compare this with sponge use at every intercourse. Recruitment problems and discontinuation forced the early termination of this study, but qualitative information about compliance and acceptability was collected. Common sponge problems were reported as were misuses of the sponge, but problems and misuse were not related. Determination of the fertile phase was reportedly easy, but complaints of and discontinuation for inconvenience occurred. For unplanned pregnancies, contraceptive behaviors around the time of conception are presented.