title: Ten years of experience with first-trimester screening for fetal aneuploidy employing biochemistry from gestational weeks 6+0 to 13+6.
abstract: OBJECTIVE
  To validate the performance of first-trimester screening for fetal aneuploidy employing blood samples drawn in gestational weeks 6-13.
  
  
  METHODS
  Prospective combined first-trimester screening for fetal aneuploidy in Denmark was validated in two large datasets: (1) a dataset from the Central Denmark Region including 147,768 pregnancies from October 2003 to October 2013, and (2) a national dataset including 220,739 pregnancies from January 2008 to August 2011.
  
  
  RESULTS
  For trisomy 21, the weekly median multiple of the median (MoM) increased from 0.37 in week 6 to 0.70 in week 13 (pregnancy-associated plasma protein-A), and from 0.99 in week 6 to 2.68 in week 13 (free βhCG). The overall detection rate (DR) for fetal trisomy 21 was 91.2%. Employing blood samples from gestational week 9, the DR was 97% (p = 0.05). For fetal trisomy 18, trisomy 13 and triploidy, the overall DRs after first-trimester screening were 79.5, 86 and 85%. In the national dataset, the overall DR for trisomy 21 was 86.3% ranging from 89 (weeks 9 and 10) to 80% (weeks 12 and 13).
  
  
  CONCLUSIONS
  The results from both datasets show that blood sampling in gestational weeks 9-10 is a robust and high-performance strategy, which can be applied for routine first-trimester screening in clinical practice. © 2014 S. Karger AG, Basel.
authors.affiliation: Department of Clinical Biochemistry, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Niels
authors.initials: N
authors.lastname: Tørring
authors.forename: Olav Bjørn
authors.initials: OB
authors.lastname: Petersen
authors.forename: Niels
authors.initials: N
authors.lastname: Uldbjerg
mesh_terms: D000782:Aneuploidy; D025063:Chromosome Disorders / Q000097:blood / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008403:Mass Screening; D011247:Pregnancy; D011261:Pregnancy Trimester, First / Q000097:blood*; D011266:Pregnancy-Associated Plasma Protein-A / Q000378:metabolism; D011296:Prenatal Diagnosis / Q000379:methods*; D011446:Prospective Studies
chemical_list: D011266:Pregnancy-Associated Plasma Protein-A