title: [Prevalence of chromosomal abnormalities in spontaneous abortions or fetal deaths].
abstract: BACKGROUND
  Spontaneous abortion is one of the most frequent problems of pregnancy, estimated to affect, at least, one in every four women who tries to conceive. The main purpose of this work was to study the prevalence of chromosomal abnormalities in gestational losses, evaluating their relation with maternal age, gestational age and previous abortion history.
  
  
  METHODS
  Retrospective study of 401 pregnancy loss cases that have gone through cytogenetic and anatomopathologic analysis between January 2008 and June 2012, in Centro Hospitalar de S. João, Oporto.
  
  
  RESULTS
  Of the 401 cases sent to cytogenetic study, it was possible to obtain information about the chromosomal complement in 333 cases, of which 72.7% showed normal karyotype, and 27.3% abnormal karyotype. Aneuploidies represented 92.3% of the identified chromosomopathies, with trisomies being the most frequent, related with an advanced maternal age and an early gestational age. There was no agreement between the results of the cytogenetic and the anatomopathologic analysis.
  
  
  CONCLUSIONS
  The prevalence of chromosomal abnormalities, during the first trimester, is similar between sporadic and recurrent miscarriages. With increased maternal age, trisomies, the most frequent type of aneuploidy, are more likely to occur, with a mean increment in probability of 7.4% per year. A significant karyotype-pathological correlation was not established. Maternal contamination is the main obstacle to the accurate determination of the prevalence of chromosomal abnormalities. The molecular cytogenetic techniques already available can overcome the limitations of the conventional technique.
authors.affiliation: Faculdade de Medicina. Universidade do Porto. Porto. Portugal.. mimed07106@med.up.pt.
authors.forename: Raquel
authors.initials: R
authors.lastname: Bastos
authors.affiliation: Departamento de Ginecologia e Obstetrícia. Faculdade de Medicina. Universidade do Porto / Centro Hospitalar S. João. Porto. Portugal.
authors.forename: Carla
authors.initials: C
authors.lastname: Ramalho
authors.affiliation: Departamento de Genética. Faculdade de Medicina. Universidade do Porto. Portugal.
authors.forename: Sofia
authors.initials: S
authors.lastname: Dória
mesh_terms: D000022:Abortion, Spontaneous / Q000235:genetics*; D000328:Adult; D002869:Chromosome Aberrations; D025063:Chromosome Disorders / Q000453:epidemiology* / Q000235:genetics*; D005260:Female; D005313:Fetal Death / Q000209:etiology*; D006801:Humans; D008423:Maternal Age; D015995:Prevalence; D012189:Retrospective Studies