An ongoing pregnancy from two waves of follicles developing during a long follicular phase of the same cycle.

To report an ongoing pregnancy after in vitro fertilization (IVF) with ovarian stimulation using a gonadotropin-releasing hormone (GnRH) antagonist that resulted in two waves of follicular growth.Case report.University of Toronto affiliated infertility clinic.A 33-year-old woman with a 3-year history of secondary infertility.In vitro fertilization and embryo transfer.Ongoing pregnancy.This patient successfully conceived after the GnRH antagonist-induced demise of the first cohort of follicles and the emergence of a second wave of follicles followed by oocyte retrieval on cycle day 30 and fresh embryo transfer.This case report is consistent with previous observations of multiple waves of follicle recruitment and growth per cycle. The window of implantation may not be adversely affected by prolonged or even variable estrogen exposure in the follicular phase of the cycle.