While COCs containing 20 μg EE may be theoretically safer, this review did not focus on the rare events required to assess this hypothesis. Data from existing randomized controlled trials are inadequate to detect possible differences in contraceptive effectiveness. Low-dose estrogen COCs resulted in higher rates of bleeding pattern disruptions. However, most trials compared COCs containing different progestin types, and changes in bleeding patterns could be related to progestin type as well as estrogen dose. Higher follow-up rates are essential for meaningful interpretation of results.
Efficacy, cycle control, and side effects of low- and lower-dose oral contraceptives: a randomized trial of 20 micrograms and 35 micrograms estrogen preparations.
Estrogen content represents a tradeoff between cycle control and side effects, but few direct comparisons of 20 and 30/35 micrograms preparations are available. To address this issue, we conducted a randomized, open-label multicenter clinical trial comparing Alesse (20 micrograms ethinyl estradiol [EE]), Mircette (20 micrograms EE), and Ortho Tri-Cyclen (35 micrograms EE) among 463 OC starters or switchers. Bloating, breast tenderness, and nausea were approximately 50% more common in women using 35 micrograms EE as compared to 20 micrograms EE preparations. Cycle control was similar in all products, although during the first two cycles among starters; users of Mircette and Ortho Tri-Cyclen (Tri-Cyclen) exhibited better cycle control than Alesse users. Discontinuation and pregnancy rates were not significantly higher in 35 micrograms EE users.