In vitro fertilization cycle outcome after coasting in gonadotropin-releasing hormone (GnRH) agonist versus GnRH antagonist protocols.

OBJECTIVES: To compare the results of IVF cycles after coasting in patients treated with a GnRH antagonist or GnRH agonist protocol. DESIGN: A retrospective case-control study. SETTING: Infertility unit in a university-affiliated tertiary medical center. PATIENT(S): The study group included all women less than 38 years old attending the IVF unit from 2000 to 2006 in whom coasting was used. Data on E(2) levels before and after coasting, duration of coasting, number of oocytes retrieved and fertilized, embryo quality, moderate-severe ovarian hyperstimulation syndrome (OHSS), and pregnancy were collected from the files and compared between GnRH agonist (n = 329) and GnRH antagonist (n = 45) cycles. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Number of retrieved oocytes and pregnancy rates. RESULT(S): There were no between-group differences in cycle parameters. In the antagonist group, there was no need for more than 2 days of coasting. There was a significant decrease in the number of retrieved oocytes even in short periods of coasting in the antagonist group but not in the agonist group. On the day of hCG administration, E(2) levels dropped to a lower level in the antagonist cycles. The OHSS rate after coasting was 4.6% in the agonist group and 4.4% in the antagonist group. Corresponding pregnancy rates after coasting were 27.4% and 24.4%. CONCLUSION(S): The same criteria for coasting can be applied in GnRH agonist as in GnRH antagonist cycles, with a similar IVF result.