A comparative study of three oral contraceptives in Ibadan: Norinyl 1/35, Lo-Ovral and Noriday 1/50

A study of three combined oral contraceptives, Norinyl 1/35, Lo-Ovral and Noriday 1/50, was conducted at the University of Ibadan Teaching Hospital, Ibadan, Nigeria, to determine if there were differences in continuation rates and reasons for discontinuation. This report includes analysis of 150 women, all of whom were interval patients, randomly allocated to one of the above oral contraceptives between May 1984 and February 1985. Follow-up visits were scheduled at 1, 4 and 8 months after admission. Significantly more women in the Norinyl 1/35 group (P less than 0.05) reported intermenstrual bleeding, as well as an increase in the occurrence of intermenstrual bleeding compared to women in the Lo-Ovral group. There were no other differences between the groups for side-effects. The continuation rates at 8 months were 90.8% for the Norinyl 1/35 group, 94.4% for the Lo-Ovral group and 87.1% for the Noriday 1/50 group. The corresponding rates for those lost to follow-up were 26.0, 40.8 and 17.7. The rate for total discontinuations (all discontinuations including women lost to follow-up) was 34.0% for the Norinyl 1/35 group, 44.9% for the Lo-Ovral group and 29.4% for the Noriday 1/50 group. There was a significant difference in lost to follow-up rates between the Lo-Ovral group and the Noriday 1/50 group (P less than 0.05). There were no other significant differences between the groups for life table rates (P greater than 0.05). There were no pregnancies reported during the study period.