title: Is there an association between endometriosis and the risk of pre-eclampsia? A population based study.
abstract: BACKGROUND
  An association between endometriosis and reduced risk of pre-eclampsia has recently been reported. Longitudinally-linked electronic hospital records are a valuable resource for investigating such findings in a large, population-based sample. Our aim was to determine whether women with a history of endometriosis were at modified risk for pregnancy hypertension or pre-eclampsia.
  
  
  METHODS
  A population-based, longitudinal study of all women in the Australian state of New South Wales, aged from 15 to 45 years of age with a singleton birth during the period 2000-2005. Endometriosis was identified using ICD-10 codes. Endometriosis subgroups were analysed based on: (i) site of endometriosis (ovary or peritoneum), (ii) multiple (i.e. two or more) sites affected and (iii) infertility. To investigate the association between pregnancy hypertension and endometriosis, number of weeks gestation at birth and maternal age, we used logistic regression.
  
  
  RESULTS
  In the 3239 (1.6%) women with endometriosis diagnosed before their first birth, 352 (10.9%) had a diagnosis of pregnancy hypertension compared with 23,186/205,640 (11.3%) in women with no endometriosis diagnosis (OR 0.96; 95% CI 0.9-1.3). The frequency of pregnancy hypertension and pre-eclampsia was not significantly different in women with more severe endometriosis or endometriosis in conjunction with infertility when compared with those with no endometriosis. After adjusting for maternal age and weeks gestation there was still no altered risk.
  
  
  CONCLUSIONS
  We have found no evidence for an association between endometriosis and subsequent risk of either pregnancy hypertension or pre-eclampsia in this large population-based dataset.
authors.affiliation: Perinatal Research, Kolling Institute, University of Sydney, B52, Level 2, Royal North Shore Hospital, St Leonard's, NSW 2065, Sydney, Australia. rhadfield@med.usyd.edu.au
authors.forename: Ruth M
authors.initials: RM
authors.lastname: Hadfield
authors.forename: Samantha J
authors.initials: SJ
authors.lastname: Lain
authors.forename: Camille H
authors.initials: CH
authors.lastname: Raynes-Greenow
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Morris
authors.forename: Christine L
authors.initials: CL
authors.lastname: Roberts
mesh_terms: D003625:Data Collection; D004715:Endometriosis / Q000150:complications*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D009517:New South Wales / Q000453:epidemiology; D011159:Population Surveillance; D011225:Pre-Eclampsia / Q000453:epidemiology*; D011247:Pregnancy; D011249:Pregnancy Complications, Cardiovascular / Q000453:epidemiology / Q000209:etiology*; D012306:Risk