A live birth with unexpectedly low serum human chorionic gonadotropin level on day 11 after blastocyst embryo transfer: a case report

To report a very rare case of live birth with unexpectedly low serum hCG level on day 11 after blastocyst embryo transfer. Case report. Private infertility center. A 30-year-old nulliparous woman presented with PCOS and 1 year of infertility. Conventional IVF was scheduled and a long-acting agonist protocol was selected. Maternal serum hCG levels and transvaginal ultrasound exams for the embryo's well-being. The hCG level was 11.6 IU/L on day 11 after the transfer of two blastocyst embryos, which was considered as either failing or extrauterine pregnancy. After blood titration, there were delayed hCG increases. A series of transvaginal ultrasounds also indicated a delayed but normal-appearing intrauterine pregnancy. A healthy baby boy was delivered at term by means of cesarean section. A low initial serum hCG level may be associated with certain maternal or fetal characteristics and IVF treatment variables. Close conservative observation is warranted before undertaking any therapeutic intervention.