Withholding gonadotropins ("coasting") to minimize the risk of ovarian hyperstimulation during superovulation and in vitro fertilization-embryo transfer cycles.

OBJECTIVE: To evaluate superovulation (SOV) and IVF-ET cycles in which E2 levels were allowed to decrease to restrain rapid follicular growth and minimize the risk of ovarian hyperstimulation syndrome.
DESIGN: Retrospective series.
SETTING: Tertiary care infertility practice. PATIENT(S): Women who underwent SOV (n = 51) and IVF-ET (n = 93) treatment and who were at risk for OHSS. INTERVENTION(S): In SOV cycles, hMG was withheld (coasting) for >3 days before hCG administration, until follicular maturity was attained (> or = 3 follicles of > or = 18 mm) and E2 levels decreased. In IVF-ET cycles, either follicular maturity was attained before coasting (n = 63), allowing hCG administration after E2 levels decreased by >25%, or coasting occurred before follicular maturation (n = 30), necessitating the administration of additional hMG after coasting. MAIN OUTCOME MEASURE(S): Estradiol concentrations, follicle size, and pregnancy rates. RESULT(S): Estradiol concentrations usually rose for > or = 1 day after coasting began, then fell by > or = 25% while follicle numbers and mean diameters increased. No spontaneous LH surges occurred, although four SOV cycles were canceled because of excessive follicular development. Of the women who received hCG,11 of 47 (23% per cycle) conceived during SOV and 35 of 93 (37.6% per cycle) conceived during IVF-ET. Severe ovarian hyperstimulation syndrome developed in 1 woman who underwent IVF-ET. CONCLUSION(S): Coasting can safely rescue overstimulated SOV and IVF-ET cycles characterized by an excessive rise in E2 levels and/or numerous incompletely mature follicles.