Human chorionic gonadotropin levels in successful implantations after assisted reproduction techniques

To assess successful implantation and early postimplantation embryonic development in assisted reproduction techniques, serum human chorionic gonadotropin (hCG) levels in early gestation in pregnancies with a singleton live birth as the outcome were evaluated. The study was performed as a prospective cohort study of patients undergoing in vitro fertilization (IVF) or artificial insemination by husband (AIH) following ovarian stimulation. Serum hCG levels on days 14, 16, 20 and 27 following ovulation induction with hCG were examined. Serum hCG values were significantly lower in early gestation in IVF compared with AIH, but no difference in hCG doubling times was observed. No difference in serum hCG values between IVF treatment with or without gonadotropin-releasing hormone agonist (GnRHa) was observed. Significantly lower hCG values but no difference in doubling times in early gestation in IVF compared with AIH may be explained by late but successful implantation in IVF. The mechanism for this assumed late implantation is not clear. Altered endometrial receptivity or factors of embryonic origin might explain the observed variation in hCG values and the assumed late implantation.