title: A human in vivo model for the luteoplacental shift.
abstract: OBJECTIVE
  To study the onset of early placental steroidogenesis in humans.
  
  
  METHODS
  Ovarian failure patients who were administered a constant dosage of exogenous estradiol (E2) and progesterone (P) during the luteal phase and early gestation and who conceived after transfer of donated oocytes were used to assess serum hormonal changes throughout early pregnancy.
  
  
  METHODS
  Hormonally replaced ovarian failure patients undergoing an egg donation program in an academic research environment.
  
  
  METHODS
  Nine human volunteers desiring egg donation.
  
  
  METHODS
  Replacement of E2 and P.
  
  
  METHODS
  Serum E2 and P concentrations were measured weekly throughout the patients' gestations.
  
  
  RESULTS
  Serum E2 and P levels of these patients remained low in early gestation but significantly increased 25 +/- 1.6 and 34 +/- 1.6 days post embryo transfer, respectively. Regression lines of E2 (r = 0.99; P less than 0.01) and P (r = 0.95; P less than 0.005), intersected basal hormonal levels approximately 3 weeks after transfer.
  
  
  CONCLUSIONS
  This estimate of the onset of placental steroidogenesis is equal to the 5th gestational week as calculated by the patients' last menses, approximately 3 weeks earlier than previously reported.
authors.affiliation: Jones Institute of Reproductive Medicine, Eastern Virginia Medical School, Norfolk.
authors.forename: R
authors.initials: R
authors.lastname: Scott
authors.forename: D
authors.initials: D
authors.lastname: Navot
authors.forename: H C
authors.initials: HC
authors.lastname: Liu
authors.forename: Z
authors.initials: Z
authors.lastname: Rosenwaks
mesh_terms: D003338:Corpus Luteum / Q000502:physiology*; D004958:Estradiol / Q000096:biosynthesis / Q000097:blood; D005260:Female; D005307:Fertilization in Vitro; D015181:Gamete Intrafallopian Transfer; D006801:Humans; D010920:Placenta / Q000378:metabolism / Q000502:physiology*; D011247:Pregnancy / Q000502:physiology*; D011374:Progesterone / Q000096:biosynthesis / Q000097:blood; D012044:Regression Analysis; D013997:Time Factors
chemical_list: D011374:Progesterone; D004958:Estradiol