title: Ethnicity, body mass index and risk of pre-eclampsia in a multiethnic New Zealand population.
abstract: BACKGROUND
  Pre-eclampsia rates are reported to vary by ethnicity; however, few studies include body mass index (BMI). Increasing BMI has a dose-dependent relationship with pre-eclampsia, and rates of overweight and obesity as well as ratios of body fat to muscle mass differ between ethnicities. We hypothesised that after adjusting for confounders, including ethnic-specific BMI, ethnicity would not be an independent risk factor for pre-eclampsia.
  
  
  OBJECTIVE
  To assess independent pre-eclampsia risk factors in a multiethnic New Zealand population.
  
  
  METHODS
  We performed a retrospective cohort analysis of prospectively recorded maternity data from 2006 to 2009 at National Women's Health, Auckland, New Zealand. After exclusion of infants with congenital anomalies and missing data, our final study population was 26 254 singleton pregnancies. Multivariable logistic regression analysis adjusted for ethnicity, BMI, maternal age, parity, smoking, social deprivation, diabetes, chronic hypertension and relevant pre-existing medical conditions was performed.
  
  
  RESULTS
  Independent associations with pre-eclampsia were observed in Chinese (adjusted odds ratio (aOR) 0.56, [95% CI 0.41-0.76]) and Māori (aOR 1.51, [1.16-1.96]) compared with European women. Other independent risk factors for pre-eclampsia were overweight and obesity, nulliparity, type 1 diabetes, chronic hypertension and pre-existing medical conditions.
  
  
  CONCLUSIONS
  Contrary to our hypothesis, we report an independent reduced risk of pre-eclampsia in Chinese and increased risk of pre-eclampsia in Māori women. Prospective studies are required to further explore these relationships. Other independent risk factors are consistent with international literature. Our findings may assist clinicians to stratify risk of pre-eclampsia in clinical practice.
authors.affiliation: Department of Obstetrics and Gynaecology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand. ngaire.anderson@auckland.ac.nz
authors.forename: Ngaire H
authors.initials: NH
authors.lastname: Anderson
authors.forename: Lynn C
authors.initials: LC
authors.lastname: Sadler
authors.forename: Alistair W
authors.initials: AW
authors.lastname: Stewart
authors.forename: Elaine M
authors.initials: EM
authors.lastname: Fyfe
authors.forename: Lesley M E
authors.initials: LM
authors.lastname: McCowan
mesh_terms: D044466:Asian People / Q000706:statistics & numerical data*; D015992:Body Mass Index; D016009:Chi-Square Distribution; D002908:Chronic Disease; D016001:Confidence Intervals; D003922:Diabetes Mellitus, Type 1 / Q000453:epidemiology / Q000208:ethnology; D005260:Female; D006801:Humans; D006973:Hypertension / Q000453:epidemiology / Q000208:ethnology; D016015:Logistic Models; D015999:Multivariate Analysis; D009520:New Zealand / Q000453:epidemiology; D009765:Obesity / Q000453:epidemiology* / Q000208:ethnology; D016017:Odds Ratio; D050177:Overweight / Q000453:epidemiology / Q000208:ethnology; D010298:Parity; D011225:Pre-Eclampsia / Q000208:ethnology*; D011247:Pregnancy; D012189:Retrospective Studies; D044465:White People / Q000706:statistics & numerical data*