title: Temporal effect of Afro-Caribbean race on serum pregnancy-associated plasma protein-a at 9-13 weeks' gestation in screening for aneuploidies.
abstract: OBJECTIVE
  It was the aim of this study to investigate the pregnancy characteristics that influence the measured concentrations of maternal serum-free β-human chorionic gonadotropin (β-hCG) and pregnancy-associated plasma protein-A (PAPP-A) at 9(+0)-13(+6) weeks' gestation.
  
  
  METHODS
  In singleton pregnancies attending for routine care, serum-free β-hCG and PAPP-A were measured at 9(+0)-13(+6) weeks' gestation and fetal nuchal translucency was measured at 11(+0)-13(+6) weeks. The population included 27,908 chromosomally normal and 104 trisomy 21 pregnancies. Multiple regression analysis was used to examine the pregnancy characteristics that have a significant effect on the measured concentrations of free β-hCG and PAPP-A. We also examined the impact of incorporating temporal effects on performance of screening for trisomy 21.
  
  
  RESULTS
  Serum-free β-hCG and PAPP-A concentrations were significantly affected by gestational age, maternal weight, racial origin, parity, preexisting diabetes mellitus type 2, smoking and conception by in vitro fertilization. There was a significant gestational age-dependent effect of Afro-Caribbean race on PAPP-A levels (p = 0.0005), with a weekly increase of 4.9% (95% CI 2.1-7.8).
  
  
  CONCLUSIONS
  Serum-free β-hCG and PAPP-A concentrations at 9(+0)-13(+6) weeks' gestation are affected by several pregnancy characteristics and the effect of Afro-Caribbean race on PAPP-A increases with gestational age.
authors.affiliation: School of Computing and Mathematics, Plymouth University, Plymouth, UK.
authors.forename: Susan
authors.initials: S
authors.lastname: Ball
authors.forename: David
authors.initials: D
authors.lastname: Wright
authors.forename: Danielle
authors.initials: D
authors.lastname: Sodre
authors.forename: Robert
authors.initials: R
authors.lastname: Lachmann
authors.forename: Kypros H
authors.initials: KH
authors.lastname: Nicolaides
mesh_terms: D000328:Adult; D000782:Aneuploidy; D015415:Biomarkers / Q000097:blood; D044383:Black People / Q000235:genetics*; D017691:Caribbean Region / Q000208:ethnology; D016009:Chi-Square Distribution; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000208:ethnology / Q000235:genetics; D004739:England / Q000453:epidemiology; D005260:Female; D005820:Genetic Testing; D005865:Gestational Age; D006801:Humans; D048208:Nuchal Translucency Measurement; D011237:Predictive Value of Tests; D011247:Pregnancy; D011248:Pregnancy Complications / Q000097:blood / Q000175:diagnosis / Q000208:ethnology* / Q000235:genetics*; D011266:Pregnancy-Associated Plasma Protein-A / Q000032:analysis*; D011296:Prenatal Diagnosis / Q000379:methods*; D011446:Prospective Studies; D012044:Regression Analysis; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors
chemical_list: D015415:Biomarkers; D018997:Chorionic Gonadotropin, beta Subunit, Human; D011266:Pregnancy-Associated Plasma Protein-A