In the short antagonist protocol, gonadotropin is administered starting from Day 2 of the cycle. During the administration of gonadotropins, the antagonist is introduced. The starting point of the antagonist administration and the dosage of this drug is determined by the doctor. Sometimes the doctor may add antiestrogens (Clostilbegyt). They are usually administered for 5 subsequent days (according to the regimen: 2-6 cd, 3-7 cd, 4-8 cd, 5-9 cd) at the dose and according to the regimen recommended by the doctor.