In mild stimulation of ovulation clomiphene or letrozole pills are taken for five days usually starting at day 3 of the cycle, although the treatment could be started sooner or later than day 3. This is decided by the doctor, depending on a cycle length of a woman, and her ovarian reserve. Clomiphene or letrozole pills are followed by gonadotropin injections until the follicle grows to 17-20 mm which usually takes 2-4 days. During the stimulation, one or two follicle monitoring ultrasounds should be done. Sometimes, antagonist injections are used in order to prevent ovulating ahead of time. However, this significantly increases the costs of the protocol.
Advantages of mild stimulation include using less medication, greater cost-effectiveness, lesser patient discomfort, and the risk of developing ovarian hyperstimulation syndrome is minimal. By using mild stimulation we expect to get 2-7 eggs from aspiration and there are usually no extra embryos for cryopreservation. Pregnancy rates using this method can be compared to standard stimulation, but since there is no cryopreservation the cumulative success rate is lower.
Patients who benefit from mild stimulation protocols are patients with high ovarian reserve. Mild stimulation protocols in such patients lowers the chance of ovarian hyperstimulation syndrome, which is otherwise very high. Also, because of their high ovarian reserve they may produce larger number of eggs in mild stimulation protocols, therefore they may have cryopreserved embryos as well.