Extended-cycle combined oral contraceptive pills contain estrogen and progestin, but they are taken on a longer schedule to reduce the number of periods. Instead of having a scheduled period every month, many people have bleeding about every 3 months, and some continuous versions are designed to skip periods altogether. These pills may be chosen for convenience, heavy periods, painful cramps, menstrual migraines, endometriosis-related symptoms, or wanting fewer periods. The main downside is that spotting or breakthrough bleeding can happen, especially in the first few months. Different versions may vary by hormone dose, schedule, brand/generic version, cost, bleeding pattern, and side effects.