HUMAN MENOPAUSAL GONADOTROPIN INCREASES PREGNANCY RATE IN COMPARISON WITH CLOMIPHENE CITRATE DURING REPLACEMENT CYCLES OF FROZEN THAWED PRONUCLEATE OVA/

In a prospective randomized study, the effect of two ovulation inducti on regimens on implantation rate of frozen/thawed pronucleate ova was investigated. Patients received either human menopausal gonadotrophin (HMG) or clomiphene/HMG. Ovulation induction was done on an individual basis using ultrasound and plasma 17 beta-oestradiol concentrations. Ovulation was induced with human chorionic gonadotrophin (HCG) when th e leading follicle reached a diameter of 18 mm. Pronucleate ova had be en frozen using the slow-freezing method of Lassalle et al. (1985) (Fe rtil. Steril., 44, 645- 651) and were thawed in synchrony with the age of the endometrium. Both groups of patients were comparable for age, indication for in-vitro fertilization, pre-ovulatory 17 beta-oestradio l concentration, number of large follicles and number and quality of e mbryos transferred. The only difference found was that HCG was adminis tered 1 day earlier in the HMG group compared to the clomiphene/HMG gr oup (P < 0.01). Using univariate analysis, the pregnancy rate was high er in patients stimulated, with HMG alone compared to those stimulated with clomiphene/HMG (27 versus 15% respectively; P < 0.03), when HCG was administered later in the menstrual cycle (P < 0.01) and when more and better quality embryos were transferred (P < 0.01). Using multiva riate regression analysis, the influence of the stimulation on pregnan cy rate was even more pronounced (P < 0.01) when the day of HCG admini stration and the number and quality embryos transferred were taken int o account. Therefore, we conclude that HMG alone increases pregnancy r ate compared to clomiphene/HMG during replacement cycles of frozen/tha wed pronucleate ova. These data suggest that HMG results in a better e ndometrium receptivity for embryos. This could be important not only f or embryo replacement cycles but also for ovulation induction in gener al.