Background: Following gonadotropin-releasing hormone (GnRH) agonist trigger and “freeze all” in order to prevent ovarian hyper-stimulation syndrome (OHSS), patients are usually anxious to continue immediately with a frozen embryo transfer (FET). Currently, the preferred FET protocol in based on natural or induced ovulation. Objectives: Do ovarian stimulation and GnRH-a, used to trigger final oocyte maturation, affect the reproductive axis in the next natural cycle? Design: An observational case series of 100 subsequent in vitro fertilization (IVF) patients to whom GnRH-a (Triptorelin 0.2 mg) was given for final oocyte maturation in the context of ovarian hyper-stimulation syndrome prevention, followed by embryos “freeze all”. Methods: In the next natural cycle, patients were followed to detect a dominant follicle (≥17 mm), at which time ovulation was triggered with human chorionic gonadotropin (hCG, 250 µg), and FET was scheduled according to embryo’s age on freezing day. Results: Whereas natural ovulation according to pre-IVF treatment was predicted to be on cycle day 14, the actual hCG-scheduled ovulation in our patients was on day 21. In eight patients, follicular activity was not detected after 15–28 days; therefore, the natural cycle frozen embryo transfer approach was abandoned. Conclusions: Ovarian stimulation and GnRH-a used to trigger final oocyte maturation in IVF patients inhibits the reproductive axis for days. Therefore, natural ovulation in the subsequent cycle may be deferred for about one week relative to the patient’s pre-IVF menstrual cycle pattern. This may help schedule clinic visits to optimize monitoring efficiency.
Breizman et al. (Mon,) studied this question.