"Coasting" does not adversely affect cycle outcome in a subset of highly responsive in vitro fertilization patients

Objective: To study the effect of postponing hCG administration while continuing daily GnRH agonist therapy ("coasting") on highly responsive patients undergoing IVF-ET. Design: Retrospective analysis. Setting: University-affiliated Center for Fertility and Reproductive Medicine. Patient(s): Patients undergoing IVF-ET from March 1995 to March 1997. Intervention(s): Three groups of IVF-ET patients were compared to explore the effect of coasting on cycle outcome: a group of highly responsive coasted patients, a group of equally responsive noncoasted patients, and an age-matched normally responsive control group. Two groups of coasted patients were also compared to assess the effect of E₂ levels at the time that they met the follicular criteria for hCG administration. Last, the effect of varying coast duration was examined by regression analysis. Main Outcome Measure(s): Patient characteristics, outcome parameters, and incidence of ovarian hyperstimulation syndrome (OHSS). Result(s): Coasting had no detrimental effect on cycle outcome in the subset studied. Regression analysis, however, suggests an inverse relationship between coast duration and the number of mature oocytes retrieved as well as the clinical pregnancy rate. Conclusion(s): Coasting in the studied subset of IVF patients did not adversely affect cycle outcome parameters or the incidence of OHSS, but prolonged coasting intervals may impair IVF cycle outcome.