title: Validation of correction factors for serum markers for first-trimester Down syndrome screening in singleton pregnancies conceived with assisted reproduction.
abstract: OBJECTIVE
  To validate previously computed correction factors for free β-human chorionic gonadotrophin (fβ-hCG) and pregnancy-associated plasma protein-A (PAPP-A) in in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) pregnancies with hormone treatment and to determine the effect on false-positive rate (FPR).
  
  
  METHODS
  Retrospective study on 249 IVF and 250 ICSI cases and 20,190 controls. Correction factors 1.42 (PAPP-A), 1.17 (fβ-hCG) in IVF; 1.56 (PAPP-A) in ICSI were applied on the absolute serum concentrations. Analysis was done on log10-transformed multiples of medians (MoMs).
  
  
  RESULTS
  In the controls, mean PAPP-A and fβ-hCG MoM were 1.004 and 1.062. Before correction, mean PAPP-A MoM was significantly lower in IVF (0.757; p < 0.001) and in ICSI (0.671; p < 0.001) and after correction comparable (1.071; p = 0.053 in IVF; 1.048; p = 0.178 in ICSI). Before correction, mean fβ-hCG MoM was comparable (1.054; p = 0.59 in IVF and 1.051; p = 0.56 in ICSI) and after correction significantly higher in IVF (1.241; p < 0.001). After correction the likelihood for receiving a false-positive result was 1.03 in IVF pregnancies (95% CI 0.98-1.09; p = 0.248) and 1.02 in ICSI pregnancies (95% CI 0.97-1.07; p = 0.448).
  
  
  CONCLUSIONS
  After correction the FPR in IVF and ICSI pregnancies with hormone treatment reduces to the observed FPR in the controls.
authors.affiliation: Department of Obstetrics and Gynecology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Melanie A J
authors.initials: MA
authors.lastname: Engels
authors.forename: Eva
authors.initials: E
authors.lastname: Pajkrt
authors.forename: Dominique T
authors.initials: DT
authors.lastname: Groot
authors.forename: Roel
authors.initials: R
authors.lastname: Schats
authors.forename: Jos W R
authors.initials: JW
authors.lastname: Twisk
authors.forename: John M G
authors.initials: JM
authors.lastname: van Vugt
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood*; D015331:Cohort Studies; D004314:Down Syndrome / Q000097:blood* / Q000175:diagnosis*; D005189:False Positive Reactions; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D009426:Netherlands; 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; D020554:Sperm Injections, Intracytoplasmic
chemical_list: D015415:Biomarkers; D018997:Chorionic Gonadotropin, beta Subunit, Human; D011266:Pregnancy-Associated Plasma Protein-A; C579283:PAPPA protein, human