title: Early detection of cell-free fetal DNA in maternal plasma.
abstract: OBJECTIVE
  We aimed to establish the earliest gestational age at which fetal DNA in maternal plasma could be detected and whether this was reliable at 12-13 weeks' gestation.
  
  
  METHODS
  A prospective observational cohort study of 32 pregnancies either after IVF or before prenatal diagnosis by CVS. Maternal blood was taken and RT-PCR was carried out to detect the multi-copy Y chromosome associated DSY14 gene. The end point was gender as assessed at delivery or on karyotype.
  
  
  RESULTS
  Y signal was obtained as early as 14 days post conception (4 weeks' gestation) and has a good prediction rate by 12 weeks' gestation.
  
  
  CONCLUSIONS
  Free fetal DNA allows very early prediction of fetal sex in some cases and could be useful for clinical use for X-linked conditions by the end of the first trimester.
authors.affiliation: Fetal Medicine Research Unit, Division of Obstetrics and Gynaecology, University of Bristol, Bristol, UK. s.illanes@bristol.ac.uk
authors.forename: S
authors.initials: S
authors.lastname: Illanes
authors.forename: M
authors.initials: M
authors.lastname: Denbow
authors.forename: C
authors.initials: C
authors.lastname: Kailasam
authors.forename: K
authors.initials: K
authors.lastname: Finning
authors.forename: P W
authors.initials: PW
authors.lastname: Soothill
mesh_terms: D000328:Adult; D015193:Chorionic Villi Sampling; D041322:Chromosomes, Human, Y; D004247:DNA / Q000097:blood*; D005260:Female; D005865:Gestational Age; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D011247:Pregnancy; D011261:Pregnancy Trimester, First / Q000097:blood; D011446:Prospective Studies; D015203:Reproducibility of Results; D012732:Sex Determination Analysis / Q000379:methods*; D020554:Sperm Injections, Intracytoplasmic
chemical_list: D004247:DNA