Generally when lifestyle changes and oral ovulation-promoting drugs are ineffective, ovulation-inducing treatment with injectable drugs for ovulation induction can be chosen. Depending on the type of drug, different drug dosage forms and the patient’s own ovarian condition, drug injections will be chosen to be used during or after menstruation, and the dosage will be chosen according to the patient’s needs, including different treatment purposes, for example, if the patient wants to have intercourse naturally, one follicle maturation is good. In case of IUI then no more than three follicles should be used. In case of IVF with in vitro fertilization, slightly more are needed so that more options are available, so that five or six follicles may be needed and therefore different doses of medication are chosen. When these follicles reach a mature diameter, which is around 18mm, a shot of HCG and GnRH agonist, which finally trigger the maturation of the egg, is given to induce follicle development.