title: How low is too low? Cycle day 28 estradiol levels and pregnancy outcomes.
abstract: OBJECTIVE
  To determine the utility of cycle day 28 estradiol (E2) levels in predicting pregnancy outcomes after IVF.
  
  
  METHODS
  Retrospective, cohort study.
  
  
  METHODS
  Academic medical center.
  
  
  METHODS
  All IVF cycles resulting in a positive pregnancy test result at our center between January 2007 and December 2012 were included.
  
  
  METHODS
  In vitro fertilization with fresh embryo transfer.
  
  
  METHODS
  A total of 5,471 IVF cycles were identified. Cycles were stratified by day-28 E2 level (pg/mL) into three groups: A: ≤50; B: 51-100; and C: >100. Outcomes measured were live birth, clinical pregnancy, biochemical, ectopic, and spontaneous abortion rates.
  
  
  RESULTS
  There were 806, 588, and 4,077 IVF pregnancies in groups A, B, and C, respectively. Live birth rates were lower in groups A (15.4%) and B (41.2%) compared with group C (77.4%), representing decreased odds of live birth in patients with E2 levels of ≤50 pg/mL (odd ratio 0.05, 95% confidence interval 0.04-0.07) and in patients with levels of 51-100 pg/mL (odds ratio 0.20, 95% confidence interval 0.17-0.25) compared with patients with levels >100 pg/mL. Rates of biochemical and ectopic pregnancies were higher in groups A (66.5%, 6.20%) and B (30.7%, 3.57%) compared with group C (7.31%, 0.66%). An hCG level <50 mIU/mL was associated with increased odds of a biochemical pregnancy and decreased odds of a live birth.
  
  
  CONCLUSIONS
  Low E2 levels early in IVF pregnancies are associated with poorer pregnancy outcomes. Estradiol can be used alone or in conjunction with hCG levels to predict the odds of a live birth.
authors.affiliation: The Ronald O. Perelman and Claudia Cohen Center for Reproductive Medicine, Weill Cornell Medical College, New York, New York.
authors.forename: Alexis P
authors.initials: AP
authors.lastname: Melnick
authors.affiliation: The Ronald O. Perelman and Claudia Cohen Center for Reproductive Medicine, Weill Cornell Medical College, New York, New York.
authors.forename: Nigel
authors.initials: N
authors.lastname: Pereira
authors.affiliation: The Ronald O. Perelman and Claudia Cohen Center for Reproductive Medicine, Weill Cornell Medical College, New York, New York.
authors.forename: Erin M
authors.initials: EM
authors.lastname: Murphy
authors.affiliation: The Ronald O. Perelman and Claudia Cohen Center for Reproductive Medicine, Weill Cornell Medical College, New York, New York.
authors.forename: Zev
authors.initials: Z
authors.lastname: Rosenwaks
authors.affiliation: The Ronald O. Perelman and Claudia Cohen Center for Reproductive Medicine, Weill Cornell Medical College, New York, New York. Electronic address: sdspando@med.cornell.edu.
authors.forename: Steven D
authors.initials: SD
authors.lastname: Spandorfer
mesh_terms: D000328:Adult; D015331:Cohort Studies; D004624:Embryo Transfer / Q000379:methods / Q000639:trends*; D004958:Estradiol / Q000378:metabolism*; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods / Q000639:trends; D006801:Humans; D007247:Infertility, Female / Q000097:blood* / Q000628:therapy*; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology; D012189:Retrospective Studies
chemical_list: D004958:Estradiol
keywords: Early pregnancy; IVF; estradiol level; predictive value