Effects of profound suppression of luteinizing hormone during ovarian stimulation 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 were explored in normal women during treatment with a gonadotrophin-releasing hormone analogue and exogenous purified follicle stimulating hormone. Ovarian responses to treatment and the capacity of supernumerary embryos to undergo blastocyst formation were examined in groups of patients defined by the concentration of plasma LH in the mid-follicular phase. Concentrations less than or equal to 0.5 IU/l diagnosed the group with profoundly suppressed LH (<LH, n = 20), which was compared with the remaining patients (nLH, n = 41), The <LH group showed lower oestradiol concentrations at human chorionic gonadotrophin administration, while the total follicular development estimated by the total follicular diameters was similar in both groups. The oestradiol secreted per follicle, estimated by the circulating concentration per mm total follicular diameter, was significantly lower in the <LH group. The combined effects of a trend to lower yield of oocytes (not significant) and a lower fertilization rate (not significant) resulted in a significantly reduced quantity of embryos available for cryopreservation after the fresh transfer. Supernumerary embryos mere cultured for 7 days to determine 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 with 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 of those embryos, represented by the ability to form blastocysts in vitro, was unaffected.