title: First-trimester aneuploidy screening: is there a maternal age at which it loses effectiveness?
abstract: OBJECTIVE
  To determine the maternal age at which the likelihood of a "screen-positive" result justifies diagnostic testing.
  
  
  METHODS
  A retrospective review of women who presented for first-trimester screening using nuchal translucency (NT) measurements with or without serum biochemistry between January 2000-December 2011. Using cutoffs of 1:300, 1:270, and 1:200, the Trisomy 21 (T21) screen-positive rates were stratified by maternal age.
  
  
  RESULTS
  A total of 6,927 women underwent first-trimester screening; women with multiple gestations and/or using donor oocytes were excluded. Of the remaining women, 4,882 had combined NT and biochemistry results, while 1,767 had NT without serum screening results. Screen-positive rates were stratified by maternal age. An increase in the screen-positive rate is noted for both groups after age 40 but is more pronounced after age 43, where the screen-positive rate is 97.8% and 63.0% using cutoffs of 1:300 for the NT and NT and Biochemistry groups, respectively.
  
  
  CONCLUSIONS
  Women undergoing first-trimester screening at age 40 have approximately 30% likelihood of screening positive for T21. This rate increases to roughly 70-90% at age 44. This information will affect the counseling of patients who are considering prenatal screening versus diagnosis.
authors.forename: Gregory W
authors.initials: GW
authors.lastname: Lau
authors.forename: Daniele S
authors.initials: DS
authors.lastname: Feldman
authors.forename: Carlos M
authors.initials: CM
authors.lastname: Morales
authors.forename: Deebra
authors.initials: D
authors.lastname: Smith
authors.forename: Rennatha
authors.initials: R
authors.lastname: Edwards
authors.forename: John
authors.initials: J
authors.lastname: Williams
mesh_terms: D000328:Adult; D004314:Down Syndrome / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008423:Maternal Age; D008875:Middle Aged; D048208:Nuchal Translucency Measurement; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011266:Pregnancy-Associated Plasma Protein-A / Q000032:analysis; D011296:Prenatal Diagnosis / Q000379:methods* / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D011266:Pregnancy-Associated Plasma Protein-A