title: Early β-human chorionic gonadotropin trends in vanishing twin pregnancies.
abstract: OBJECTIVE
  To describe the early β-hCG trends in vanishing twins compared with normally progressing singleton and twin pregnancies.
  
  
  METHODS
  Retrospective cohort study.
  
  
  METHODS
  University-based infertility clinic.
  
  
  METHODS
  Women undergoing fresh IVF/intracytoplasmic sperm injection (ICSI) cycles between 1998 and 2010.
  
  
  METHODS
  Early β-hCG level increase in vanished twin pregnancies was compared with the level increase in normally progressing singleton and twin pregnancies.
  
  
  METHODS
  Two-day percent increase in β-hCG level.
  
  
  RESULTS
  Pregnancies with vanishing twins demonstrated a significantly lower mean 2-day percent increase in β-hCG level than singletons and twins (114.3% vs. 128.8% and 125.4%, respectively). Vanishing twins arresting at earlier developmental stages demonstrated significantly further reduced β-hCG level increases. Infrequently, all groups had β-hCG level increases less than previously established clinical thresholds that led to a live birth.
  
  
  CONCLUSIONS
  Early β-hCG level increases are slower in vanishing twins than in singleton and twin pregnancies, with the slowest increases seen when the spontaneous fetal losses occur at earlier developmental stages. All increases, however, are within clinically accepted normal limits. Therefore, abnormal β-hCG level increases should not be attributed to a vanishing twin. Of note, an abnormal β-hCG level trend--even an initial decrease--does not preclude live birth, even in a singleton pregnancy.
authors.affiliation: Department of Obstetrics and Gynecology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA. pbrady2@partners.org
authors.forename: Paula C
authors.initials: PC
authors.lastname: Brady
authors.forename: Katharine F
authors.initials: KF
authors.lastname: Correia
authors.forename: Stacey A
authors.initials: SA
authors.lastname: Missmer
authors.forename: Mark D
authors.initials: MD
authors.lastname: Hornstein
authors.forename: Sara E
authors.initials: SE
authors.lastname: Barton
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood*; D015331:Cohort Studies; D005260:Female; D005327:Fetal Resorption / Q000097:blood* / Q000175:diagnosis*; D006801:Humans; D011247:Pregnancy; D059285:Pregnancy, Twin / Q000097:blood*; D011446:Prospective Studies; D012189:Retrospective Studies; D013997:Time Factors
chemical_list: D015415:Biomarkers; D018997:Chorionic Gonadotropin, beta Subunit, Human