title: Hypertensive disorders in twin pregnancy.
abstract: OBJECTIVE
  To compare the incidence and severity of pregnancy-induced hypertensive disorders in twin pregnancy and in singleton gestation.
  
  
  METHODS
  Case-control study in the setting of a University Hospital. Each pregnancy of a consecutive series of 187 twin pregnancies attending the antenatal clinic and booked before a gestational age of 24 weeks was matched for maternal age, parity, and gestational age at delivery with a singleton pregnancy delivered in the same year. Primary end points of the analysis of the course and outcome of pregnancy were pregnancy-induced hypertension and proteinuric pre-eclampsia.
  
  
  RESULTS
  In the twin pregnancy group, 21% of patients met the criteria for the diagnosis of a pregnancy-induced hypertensive disorder, compared with 13% in the singleton pregnancy group (P < 0.05). The difference was due to a significantly higher incidence of pregnancy-induced hypertension in twin (15%) than in singleton (6%) pregnancy (P < 0.05), in particular in nulliparous women. The incidence of pre-eclampsia was similar in twin (6%) and singleton pregnancies (6.5%), without a difference in severity and in the occurrence of the HELLP syndrome.
  
  
  CONCLUSIONS
  The incidence of non-proteinuric pregnancy-induced hypertension, but not of proteinuric pre-eclampsia, is increased in twin pregnancy.
authors.affiliation: Institute of Obstetrics and Gynecology, Erasmus University School of Medicine and Health Sciences, Rotterdam, The Netherlands.
authors.forename: J G
authors.initials: JG
authors.lastname: Santema
authors.forename: I
authors.initials: I
authors.lastname: Koppelaar
authors.forename: H C
authors.initials: HC
authors.lastname: Wallenburg
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D005260:Female; D005865:Gestational Age; D006801:Humans; D006973:Hypertension / Q000453:epidemiology* / Q000503:physiopathology; D015994:Incidence; D008875:Middle Aged; D011225:Pre-Eclampsia / Q000453:epidemiology / Q000503:physiopathology; D011247:Pregnancy; D011249:Pregnancy Complications, Cardiovascular / Q000453:epidemiology* / Q000503:physiopathology; D011272:Pregnancy, Multiple; D012720:Severity of Illness Index; D014427:Twins