title: Relationship between obstetric history and Rh(D) alloimmunization severity.
abstract: BACKGROUND
  To evaluate the relationship between obstetric history and Rh(D) alloimmunization severity, employing the gestational age at the first intrauterine fetal transfusion (IUT) as an indicator of this severity.
  
  
  METHODS
  From 1996 to 2006, Rh(D) alloimmunized pregnancies submitted to IUT had their data assessed. Gestational age at the first IUT was modeled as a linear outcome. The associations between obstetric history variables, anti-Rh(D) antibodies titer and gestational age at the first IUT were analyzed. Statistics are presented with 95% confidence intervals (P < 0.05).
  
  
  RESULTS
  A total of 82 non-hydropic anemic fetuses, ensuing in 92.7% (n = 76) of perinatal survival, were submitted to IUT. Nineteen (23,2%) pregnant women did not present with any previous stillbirth, neonatal death, IUT, hydrops or neonatal exchange transfusion (group 1); and 63 (76.8%) reported at least one of these events (group 2). Gestational age at the first IUT differed significantly between the groups (P = 0.0001). For group 1, it ranged from 24 to 35 weeks (median 32.5 weeks), whereas for group 2 it ranged from 19 to 34 weeks (median 27 weeks). In the multivariated analysis, previous neonatal death (P = 0.040), previous IUT (P = 0.000) and previous neonatal exchange transfusion (P = 0.036) were independently associated with the gestational age at the first IUT.
  
  
  CONCLUSIONS
  The evaluation of the obstetrical history is an important diagnostic tool for predicting Rh(D) alloimmunization severity. Alloimmunized pregnant women who reported previous neonatal death(s), neonatal exchange transfusion(s) or IUT(s) should receive a closer fetal surveillance due to the risk of a higher rate of fetal hemolysis and the need of an earlier IUT.
authors.affiliation: Fetal Medicine Unit, Department of Obstetrics, Fernandes Figueira Institute, Oswaldo Cruz Foundation, Rui Barbosa Avenue 716, Flamengo, CEP: 22250-020, Rio de Janeiro (RJ), Brazil. lobato@iff.fiocruz.br
authors.forename: Gustavo
authors.initials: G
authors.lastname: Lobato
authors.forename: Cristina Silveira
authors.initials: CS
authors.lastname: Soncini
mesh_terms: D000743:Anemia, Hemolytic / Q000628:therapy; D000906:Antibodies / Q000097:blood; D001805:Blood Transfusion, Intrauterine / Q000706:statistics & numerical data; D005260:Female; D005315:Fetal Diseases / Q000628:therapy; D005865:Gestational Age; D020073:Gravidity; D006801:Humans; D015160:Hydrops Fetalis / Q000453:epidemiology; D007231:Infant, Newborn; D015999:Multivariate Analysis; D011247:Pregnancy; D012203:Rh Isoimmunization / Q000628:therapy*; D012204:Rh-Hr Blood-Group System / Q000276:immunology*; D012720:Severity of Illness Index; D050497:Stillbirth / Q000453:epidemiology
chemical_list: D000906:Antibodies; D012204:Rh-Hr Blood-Group System