title: [Optimum time of maternal blood sampling for prenatal diagnosis with fetal cells].
abstract: OBJECTIVE
  To investigate the optimum time of maternal blood sampling for prenatal diagnosis with fetal cells.
  
  
  METHODS
  Zinc-finger protein gene on Y-chromosome (ZFY) sequences were examined by nested polymerase chain reaction in the peripheral blood of 41 pregnant women.
  
  
  RESULTS
  19 pregnant women carrying male fetuses, and another 22 women found to carry female fetuses. Among the 19 pregnant women, ZFY gene were detected in 1/19 (5.3%) cases before the 6th gestational weeks, in 13/19 (68.4%) before the 11th weeks, and in 18/19 (95.0%) before the 14th weeks. The results of this study clearly demonstrated that the gender prediction obviously increased along with the gestational weeks. ZFY gene was not detected in the blood of another 22 women carrying female fetuses. The final accuracy of 97.8% (40/41) was attained in all cases.
  
  
  CONCLUSIONS
  The optimum time of maternal blood sampling is at the 14th week, and the appearance of fetal cells in maternal blood was quite case-variable from the 6th to 14th weeks.
authors.affiliation: National Research Institute for Family Planning, Beijing.
authors.forename: X
authors.initials: X
authors.lastname: Ma
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.forename: L
authors.initials: L
authors.lastname: Wang
mesh_terms: D000328:Adult; D004268:DNA-Binding Proteins / Q000032:analysis; D005260:Female; D006801:Humans; D016133:Polymerase Chain Reaction; D011247:Pregnancy / Q000097:blood*; D011261:Pregnancy Trimester, First; D011296:Prenatal Diagnosis; D012732:Sex Determination Analysis; D013997:Time Factors; D014998:Y Chromosome; D016335:Zinc Fingers
chemical_list: D004268:DNA-Binding Proteins