EFFECTS OF PROFOUND SUPPRESSION OF LUTEINIZING-HORMONE DURING OVARIANSTIMULATION ON FOLLICULAR ACTIVITY, OOCYTE AND EMBRYO FUNCTION IN CYCLES STIMULATED WITH PURIFIED FOLLICLE-STIMULATING-HORMONE

The effects of profound suppression of circulating luteinizing hormone (LH) during the follicular phase of in-vitro fertilization cycles wer e explored in normal women during treatment with a gonadotrophin-relea sing hormone analogue and exogenous purified follicle stimulating horm one. Ovarian responses to treatment and the capacity of supernumerary embryos to undergo blastocyst formation were examined in groups of pat ients defined by the concentration of plasma LH in the mid-follicular phase. Concentrations less than or equal to 0.5 IU/l diagnosed the gro up with profoundly suppressed LH (<LH, n = 20), which was compared wit h the remaining patients (nLH, n = 41), The <LH group showed lower oes tradiol concentrations at human chorionic gonadotrophin administration , while the total follicular development estimated by the total follic ular diameters was similar in both groups. The oestradiol secreted per follicle, estimated by the circulating concentration per mm total fol licular diameter, was significantly lower in the <LH group. The combin ed effects of a trend to lower yield of oocytes (not significant) and a lower fertilization rate (not significant) resulted in a significant ly reduced quantity of embryos available for cryopreservation after th e fresh transfer. Supernumerary embryos mere cultured for 7 days to de termine blastocyst development rates, and the degree of LH suppression made no difference to embryo developmental competence (nLH, 23%; <LH, 27%), or the rates of blastocyst formation. The group of patients wit h profoundly suppressed mid-follicular phase LH showed a reduced yield of oocytes and embryos which resulted in significantly fewer embryos available for cryopreservation. However, the developmental potential o f those embryos, represented by the ability to form blastocysts in vit ro, was unaffected.