Some women who do not respond or do not get pregnant following CC therapy will be considered for injectable gonadotropins. The gonadotropic hormones or gonadotropins are FSH and LH. In the past, these two hormones were isolated from urine of post-menopausal women, which is why they were also known as Urofollitropins. They contained roughly about 50% of each hormone. It was felt that there were larger amounts of LH than was physiologically needed. FSH products with lower LH content (5% or less) were introduced later. Recently, pure FSH preparations produced by DNA recombinant technologies were placed on the market. It is not clear yet if the lack of LH in the FSH injections will have a positive impact on the general population using these compounds. However, it is clinically significant to use low or no LH contaminated FSH compounds in specific cases such as patients with polycystic ovarian syndrome.

The rise of FSH observed with CC therapy may not be large enough to provide sufficient stimulation to achieve ovulation and pregnancy. In a number of cases, women will respond better if higher and sustained levels of FSH can be obtained. Exogenous gonadotropins will work in the majority of cases where CC therapy did not. The goal of any form of ovarian stimulation is to achieve the development of a single follicle. However, the response of patients to the gonadotropins is very diverse and often associated to patient’s age, number of follicles in the ovaries, presence of genetic or endocrine conditions. Fortunately, a number of different stimulation protocols have been described. Low doses of FSH given for a long period of time ("low and slow protocols") are recommended for patients with a very large number of small follicles. Those with lesser numbers of follicles may require a more aggressive approach with larger amounts of FSH to achieve a similar ovarian response. In general, the medication is administered for a period of 7-12 days. In rare cases a single follicle develops. Most of the time several follicles mature and may release eggs for fertilization. This may lead to a high incidence of multiple pregnancies if proper monitoring and actions are not in place. Close evaluation of blood estrogens and ovarian ultrasound monitoring must be a standard practice to avoid hyperstimulation.