Ovarian stimulation, including in vitro fertilisation.

The stimulation regimens and the results of ovulation induction in anovulatory patients and in patients suffering from a Luteinized Unruptured Follicle (LUF) syndrome are discussed as well as the findings concerning superovulation in IVF cycles. The percentage of multiple pregnancies (less than or equal to 20 p. cent) is acceptable, due to the accurate daily performance of hormonal determinations. The pregnancy rate is lower in a LUF population, than in anovulatory patients. This is likely due to the unknown pathophysiology of the LUF syndrome. Compared to natural cycles, the maximum serum LH concentration is reduced in stimulated cycles although multiple oocytes have to mature in superovulated patients. A possible explanation for these reduced LH surges could be an increase in inhibin -like substances. There is still a need for more research to find out the real interaction between the follicle and the hypothalamic-hypophysial axis.