title: [Association between maternal heterozygosity for five blood groups and reproductive success].
abstract: BACKGROUND
  In man, blood groups are polymorphic genetic systems. Maternal fetal incompatibility phenomena should lead to an elimination rather than a maintenance of these polymorphisms. A possible mechanism that could explain the persistence of these polymorphisms in natural populations is a selective reproductive advantage of heterozygous individuals.
  
  
  OBJECTIVE
  To explore the relationship between maternal heterozygosity for five blood groups and some obstetrical variables related to gestational success.
  
  
  METHODS
  Using a case control design, to every mother giving birth to a malformed child a consecutive mother, whose offspring was normal, was assigned as control. All women were typified for ABO, Rh, Kidd, MNSs and Duffy blood groups.
  
  
  RESULTS
  Two hundred two women were studied. There was only one stillbirth, born from a heterozygous mother for all analyzed loci. Mothers that were heterozygous or homozygous for all loci had a higher frequency of malformed children. Women homozygous for all loci had a higher frequency of living offspring than the rest of the sample.
  
  
  CONCLUSIONS
  Heterozygous mothers for these genetic systems have a reproductive disadvantage.
authors.affiliation: Facultad de Medicina, Universidad de los Andes.
authors.forename: C G
authors.initials: CG
authors.lastname: Christoph
authors.forename: M I
authors.initials: MI
authors.lastname: Thumala
authors.forename: J
authors.initials: J
authors.lastname: Nazer
authors.forename: L
authors.initials: L
authors.lastname: Armanet
authors.forename: L
authors.initials: L
authors.lastname: Cifuentes
mesh_terms: D000022:Abortion, Spontaneous / Q000235:genetics; D001789:Blood Group Antigens / Q000009:adverse effects* / Q000235:genetics*; D016022:Case-Control Studies; D000013:Congenital Abnormalities / Q000235:genetics*; D005260:Female; D006579:Heterozygote; D006801:Humans; D007231:Infant, Newborn; D011247:Pregnancy; D011248:Pregnancy Complications; D012098:Reproduction / Q000235:genetics*
chemical_list: D001789:Blood Group Antigens
vernacular_title: Asociación entre heterocigocidad materna para cinco grupos sanguíneos y éxito reproductivo.