title: Blood group AB and factor V Leiden as risk factors for pre-eclampsia: a population-based nested case-control study.
abstract: BACKGROUND
  Pre-eclampsia is an important cause of maternal morbidity and mortality. Its etiology is still unknown. Clinical symptoms correlate with activation of coagulation and inherited thrombophilia has been associated with pre-eclampsia. ABO blood group has been associated with thrombotic disorders and pre-eclampsia. We assessed ABO blood group, seven thrombophilia associated polymorphisms, and anti-beta2-glycoprotein I antibodies as risk factors for pre-eclampsia.
  
  
  METHODS
  We performed a population-based nested case-control study of 100,000 consecutive pregnancies in Finland. Cases and controls were identified by combining national registers and medical records were reviewed. We studied 248 cases fulfilling strict criteria for pre-eclampsia and 679 controls. Severe pre-eclampsia, early pre-eclampsia, and pre-eclampsia with intra-uterine growth restriction (IUGR) were analyzed separately.
  
  
  RESULTS
  Blood group AB increased the risk for pre-eclampsia as a whole (OR 2.1, 95% CI 1.3-3.5), and in the three subgroups (OR 2.3, 3.8, 3.4; 95% CI 1.3-3.9, 2.0-7.1, 1.6-7.1). FV Leiden increased the risk as a whole (OR 1.7, 95% CI 0.8-3.9), and in the three subgroups, although not statistically significantly. Anti-beta2-glycoprotein I antibodies were not associated with pre-eclampsia. High body mass index, diabetes, first pregnancy, and twin pregnancy increased the risk from 1.5-fold to 8.2-fold.
  
  
  CONCLUSIONS
  Our results confirm and extend the prior observation of blood group AB being a risk factor for pre-eclampsia. ABO blood group is known from all pregnant women. The value of blood group as risk factor for pre-eclampsia should be further assessed in prospective studies. In this study, FV Leiden was not statistically significant risk factor.
authors.affiliation: Department of Hemostasis, Finnish Red Cross Blood Service, Helsinki, Finland. leena.hiltunen@bts.redcross.fi
authors.forename: Leena M
authors.initials: LM
authors.lastname: Hiltunen
authors.forename: Hannele
authors.initials: H
authors.lastname: Laivuori
authors.forename: Anna
authors.initials: A
authors.lastname: Rautanen
authors.forename: Risto
authors.initials: R
authors.lastname: Kaaja
authors.forename: Juha
authors.initials: J
authors.lastname: Kere
authors.forename: Tom
authors.initials: T
authors.lastname: Krusius
authors.forename: Mikko
authors.initials: M
authors.lastname: Paunio
authors.forename: Vesa
authors.initials: V
authors.lastname: Rasi
mesh_terms: D000293:Adolescent; D000328:Adult; D001789:Blood Group Antigens / Q000235:genetics*; D016022:Case-Control Studies; D005165:Factor V / Q000235:genetics*; D005260:Female; D005387:Finland; D006801:Humans; D016017:Odds Ratio; D044382:Population Groups / Q000235:genetics*; D011225:Pre-Eclampsia / Q000097:blood* / Q000209:etiology / Q000235:genetics*; D011247:Pregnancy; D012307:Risk Factors; D055815:Young Adult
chemical_list: D001789:Blood Group Antigens; C095381:factor V Leiden; D005165:Factor V