title: Median levels of serum biomarkers of fetal Down syndrome detected during the first trimester among pregnant Thai women.
abstract: OBJECTIVE
  To develop Thai-specific medians of serum pregnancy-associated plasma protein A (PAPP-A) and free β-human chorionic gonadotropin (hCG) levels during the first trimester of pregnancy and to compare these values to a Caucasian-specific model for the detection of fetal Down syndrome.
  
  
  METHODS
  Serum concentrations of PAPP-A and free β-hCG were measured during the first trimester in a group of 2339 Thai women undergoing normal singleton pregnancies.
  
  
  RESULTS
  Thai reference ranges of PAPP-A and free β-hCG were established by gestational age (70-98 days). The equation of best fit for PAPP-A was: predicted median PAPP-A level=28.767 - 0.781×(gestational age in days)+0.006×(gestational age in days)(2); r=0.986. The equation of best fit for free β-hCG was: predicted median free β-hCG level=465.332×10((-0.024×gestational age in days)); r=0.881. Weight-corrected models were also derived for each biomarker. The Thai-specific reference ranges gave higher positive screening rates than the Caucasian-specific model, even after weight correction (5.1% versus 4.0%). The Thai-specific models were validated in an independent group of 302 pregnant women.
  
  
  CONCLUSIONS
  Ethnic group-specific medians for PAPP-A and free β-hCG should be incorporated during first-trimester screening for fetal Down syndrome.
authors.affiliation: Department of Obstetrics and Gynecology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
authors.forename: Suchaya
authors.initials: S
authors.lastname: Luewan
authors.forename: Supatra
authors.initials: S
authors.lastname: Sirichotiyakul
authors.forename: Yuri
authors.initials: Y
authors.lastname: Yanase
authors.forename: Kuntharee
authors.initials: K
authors.lastname: Traisrisilp
authors.forename: Theera
authors.initials: T
authors.lastname: Tongsong
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood*; D004314:Down Syndrome / Q000175:diagnosis*; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis; D006801:Humans; D008403:Mass Screening / Q000379:methods; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011266:Pregnancy-Associated Plasma Protein-A / Q000032:analysis*; D011296:Prenatal Diagnosis / Q000379:methods*; D013785:Thailand
chemical_list: D015415:Biomarkers; D018997:Chorionic Gonadotropin, beta Subunit, Human; D011266:Pregnancy-Associated Plasma Protein-A