title: First trimester biochemical screening for Down's syndrome in singleton pregnancies conceived by assisted reproduction.
abstract: BACKGROUND
  Serum biochemical markers [free betahCG (fbetahCG); pregnancy-associated plasma protein-A (PAPP-A)] used in first trimester Down's syndrome screening have not been fully investigated in pregnancies achieved by assisted reproduction techniques. We present data on pregnancies conceived by all types of assisted reproduction techniques, including pregnancies following ovum donation (OD) and a large sample by ICSI.
  
  
  METHODS
  First trimester Down's syndrome screening was performed in 1054 normal singleton pregnancies: natural conception (n = 498), ovulation induction (OS, n = 97), IVF (n = 47), ICSI (n = 222) and OD (n = 190).
  
  
  RESULTS
  No differences in maternal levels of fbetahCG and PAPP-A, measured by the Kryptor system, appeared between naturally conceived pregnancies (n = 498) and those obtained with assisted reproduction techniques (n = 556). Several differences were apparent when comparing fbetahCG levels between different technologies but PAPP-A levels only differed between OS and IVF pregnancies (P < 0.05). In a further small study, no differences were observed using frozen embryos (n = 37), preimplantation genetic diagnosis (n = 53) or sperm from testicular biopsy (n = 21).
  
  
  CONCLUSIONS
  Data accumulated so far suggest that first trimester biochemical markers either do not need any adjustments (e.g. in pregnancies obtained after OS and ICSI), or have very little impact (e.g. IVF pregnancies) or no impact (e.g. OD pregnancies) on the false positive rates.
authors.affiliation: Unidad de Medicina Materno-Fetal and Unidad de Reproducción, Instituto Universitario IVI, Universidad de Valencia, Spain. jbellver@ivi.es
authors.forename: José
authors.initials: J
authors.lastname: Bellver
authors.forename: Coral
authors.initials: C
authors.lastname: Lara
authors.forename: Sergio R
authors.initials: SR
authors.lastname: Soares
authors.forename: Alberto
authors.initials: A
authors.lastname: Ramírez
authors.forename: Antonio
authors.initials: A
authors.lastname: Pellicer
authors.forename: José
authors.initials: J
authors.lastname: Remohí
authors.forename: Vicente
authors.initials: V
authors.lastname: Serra
mesh_terms: D015415:Biomarkers / Q000097:blood; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood*; D004314:Down Syndrome / Q000097:blood / Q000175:diagnosis*; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011296:Prenatal Diagnosis / Q000379:methods* / Q000592:standards; D015203:Reproducibility of Results; D027724:Reproductive Techniques, Assisted
chemical_list: D015415:Biomarkers; D018997:Chorionic Gonadotropin, beta Subunit, Human