The effect of desogestrel, gestodene, and other factors on spotting and bleeding

Spotting and bleeding are among the most common side effects associated with oval contraceptive (OC) use and their occurrence is a prime determinant of whether a new user will continue to use OCs. Desogestrel and gestodene are two new progestins that were developed in part to minimize the occurrence of these side effects. Assessing the effect of these progestins is difficult, however, in part be cause their effects may be subtle, requiring a large sample size and possibly being overshadowed by other factors. To address these issues, we analyzed data from two comparative multicenter clinical trials that included 15,421 cycles among 2767 women. One study compared 75 mu g gestodene + 30 mu g ethinyl estradiol (EE) with 150 mu g desogestrel + 30 pg EE, the other compared the same gestodene preparation with 150 mu g desogestrel + 20 mu g EE. Both studies found a higher risk of spotting or bleeding in all cycles among users of the desogestrel-containing preparation, with the differences ranging between 20% and 70% higher for the first study and 40% and 140% in the second. These differences were statistically significant in four of six cycles in each study and persisted after controlling for consis tency and recency of OC use as well as smoking. After pooling the data and controlling for estrogen dose, the desogestrel-containing preparation was significantly associated with more frequent spotting or bleeding in five of six cycles. Smoking and consistency and recency of OC use were also independent predictors of spotting or bleeding.