Unexpected pregnancy despite extremely decreased estradiol levels during ovarian stimulation

To report two patients with ongoing pregnancies despite a dramatically sharp decrease in E(2) levels after coasting.

Case report.

Reproductive endocrinology and assisted reproduction unit of university hospital.

One 30-year-old and one 25-year-old woman, both with unexplained infertility, in whom E(2) levels increased up to 6345 and 14,275 pg/mL during ovarian hyperstimulation and decreased by 79.5% and 75.5%, respectively, after coasting.

Two IVF treatments during which coasting was performed after high E(2) levels were observed. IVF cycles were carried out despite abrupt E(2) decrease.

Development of ovarian hyperstimulation syndrome (OHSS) or fertilization, cleavage, implantation, and pregnancy rates.

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.

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 E(2) levels to a safer range; however, there has been no consistency with respect to the time of coasting or the safety rates of E(2) decrease. We believe that high rates of E(2) decrease after coasting do not have deleterious effects on implantation.