title: Embryo implantation during menstruation in the absence of adequate estradiol and progesterone support, with subsequent normal response to ovulation induction and superfetation.
abstract: OBJECTIVE
  To report an unusual case of embryo implantation and superfetation.
  
  
  METHODS
  Retrospective case analysis.
  
  
  METHODS
  Oak Brook Fertility Center.
  
  
  METHODS
  A 41-year-old woman underwent two consecutive ovarian stimulation cycles interrupted by a normal menstrual period. Ovulation and implantation occurred during both cycles. The first embryo conceived developed normally until term; the second failed to develop.
  
  
  METHODS
  None.
  
  
  METHODS
  Retrospective analysis of stored blood samples for serum E2, P, and beta-hCG levels.
  
  
  RESULTS
  Rising beta-hCG levels during menstruation indicated normal embryonic implantation in the absence of adequate E2 and P support. During subsequent ovarian stimulation, there was a normal follicular and E2 response and normal ovulation in spite of the ongoing pregnancy. The second embryo, conceived during the second cycle of stimulation, implanted but failed to develop.
  
  
  CONCLUSIONS
  This unusual case indicates that E2, P, and endometrial thickness requirements for successful implantation may not always be as critical as postulated previously. The absence of a decidual response might have facilitated superfetation.
authors.affiliation: Oak Brook Fertility Center, Illinois, USA.
authors.forename: W P
authors.initials: WP
authors.lastname: Dmowski
authors.forename: L
authors.initials: L
authors.lastname: DeOrio
authors.forename: N
authors.initials: N
authors.lastname: Rana
mesh_terms: D000328:Adult; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood; D010064:Embryo Implantation; D004958:Estradiol / Q000502:physiology*; D005260:Female; D006801:Humans; D010062:Ovulation Induction; D011247:Pregnancy; D011374:Progesterone / Q000502:physiology*; D012189:Retrospective Studies; D013476:Superfetation
chemical_list: D006063:Chorionic Gonadotropin; D018997:Chorionic Gonadotropin, beta Subunit, Human; D011374:Progesterone; D004958:Estradiol