Corpus luteum function and pregnancy rates with clomiphene citrate therapy: comparison of human chorionic gonadotrophin-induced versus spontaneous ovulation.

A total of 508 clomiphene citrate cycles with intra-uterine insemination (IUI) performed in 233 consecutive patients were studied. In 247 cycles insemination was performed 36-38 h after human chorionic gonadotrophin (HCG)-triggered ovulation; in the remaining 261 cycles IUI was performed 18-20 h after urinary luteinizing hormone (LH) kit detection of a spontaneous LH surge. Corpus luteum function, as determined by luteal phase length and mid-luteal progesterone concentrations, together with pregnancy rates were analysed. There was no difference in luteal phase parameters between spontaneous and HCG-triggered cycles when adjusting for patient age. Furthermore, the pregnancy rates did not differ between the HCG and LH kit groups, even after adjusting for patient age and number of motile spermatozoa inseminated. Additionally, the large numbers of cycles analysed provided sufficient power to detect increases in clinical pregnancy rates in spontaneous ovulatory cycles and HCG-induced ovulation of 10.1 and 2.4% respectively, using the customary significance level (alpha-type error) of 0.05. These findings indicate that pregnancy rates and corpus luteum function in carefully monitored clomiphene citrate/IUI cycles do not differ between HCG-triggered and spontaneous ovulatory cycles.