title: Maternal serum human chorionic gonadotrophin and pregnancy-associated plasma protein A in twin pregnancies in the first trimester.
abstract: OBJECTIVE
  To determine the levels of free beta-human chorionic gonadotrophin (beta-hCG) and pregnancy-associated plasma protein A (PAPP-A) in twin pregnancies in the first trimester.
  
  
  METHODS
  Serum samples were obtained from 67 pregnant women with twin pregnancies and maternal serum free beta-hCG and PAPP-A concentrations were compared with those of 4279 singleton controls between the 8th and 13th weeks of gestation.
  
  
  RESULTS
  The geometric means of chromosomally normal twin pregnancies were 1.85 MoM for free beta-hCG and 2.36 MoM for PAPP-A. There were no cases affected by Down syndrome in either group.
  
  
  CONCLUSIONS
  Twin pregnancies secrete more PAPP-A than expected on the basis of singleton controls whereas free beta-hCG production is not increased. The results of the present study can be used to establish normal reference values when introducing first trimester Down syndrome screening in prenatal care.
authors.affiliation: Department of Obstetrics and Gynecology, Oulu University Hospital, Oulu, Finland.
authors.forename: Marko
authors.initials: M
authors.lastname: Niemimaa
authors.forename: Mikko
authors.initials: M
authors.lastname: Suonpää
authors.forename: Seppo
authors.initials: S
authors.lastname: Heinonen
authors.forename: Maija
authors.initials: M
authors.lastname: Seppälä
authors.forename: Risto
authors.initials: R
authors.lastname: Bloigu
authors.forename: Markku
authors.initials: M
authors.lastname: Ryynänen
mesh_terms: D000328:Adult; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood*; D005260:Female; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D011272:Pregnancy, Multiple / Q000097:blood*; D011266:Pregnancy-Associated Plasma Protein-A / Q000032:analysis*; D012016:Reference Values; D014427:Twins
chemical_list: D018997:Chorionic Gonadotropin, beta Subunit, Human; D011266:Pregnancy-Associated Plasma Protein-A