Unexpected pregnancy despite extremely decreased estradiol levels during ovarian stimulation

ObjectiveTo report two patients with ongoing pregnancies despite a dramatically sharp decrease in E2 levels after coasting.DesignCase report.SettingReproductive endocrinology and assisted reproduction unit of university hospital.Patient(s)One 30-year-old and one 25-year-old woman, both with unexplained infertility, in whom E2 levels increased up to 6345 and 14,275 pg/mL during ovarian hyperstimulation and decreased by 79.5% and 75.5%, respectively, after coasting.Intervention(s)Two IVF treatments during which coasting was performed after high E2 levels were observed. IVF cycles were carried out despite abrupt E2 decrease.Main Outcome Measurement(s)Development of ovarian hyperstimulation syndrome (OHSS) or fertilization, cleavage, implantation, and pregnancy rates.Result(s)Two embryos (one grade A and one grade B) were transferred into the 30-year-old patient and three embryos (all grade A) were transferred into the 25-year-old patient. Neither woman developed OHSS. Two pregnancies on going at gestational weeks 20 and 14, respectively.Conclusion(s)Coasting is practiced to avoid severe complications of ovarian hyperstimulation during IVF cycles and is achieved by withholding gonadotropins. The aim of coasting is to lower E2 levels to a safer range; however, there has been no consistency with respect to the time of coasting or the safety rates of E2 decrease. We believe that high rates of E2 decrease after coasting do not have deleterious effects on implantation.