title: Relationship between obesity, ethnicity and risk of late stillbirth: a case control study.
abstract: BACKGROUND
  In high income countries there has been little improvement in stillbirth rates over the past two decades. Previous studies have indicated an ethnic disparity in the rate of stillbirths. This study aimed to determine whether maternal ethnicity is independently associated with late stillbirth in New Zealand.
  
  
  METHODS
  Cases were women with a singleton, late stillbirth (≥ 28 weeks' gestation) without congenital abnormality, born between July 2006 and June 2009 in Auckland, New Zealand. Two controls with ongoing pregnancies were randomly selected at the same gestation at which the stillbirth occurred. Women were interviewed in the first few weeks following stillbirth, or at the equivalent gestation for controls. Detailed demographic data were recorded. The study was powered to detect an odds ratio of 2, with a power of 80% at the 5% level of significance, given a prevalence of the risk factor of 20%. A multivariable regression model was developed which adjusted for known risk factors for stillbirth, as well as significant risk factors identified in the current study, and adjusted odds ratios and 95% confidence intervals were calculated.
  
  
  RESULTS
  155/215 (72%) cases and 310/429 (72%) controls consented. Pacific ethnicity, overweight and obesity, grandmultiparity, not being married, not being in paid work, social deprivation, exposure to tobacco smoke and use of recreational drugs were associated with an increased risk of late stillbirth in univariable analysis. Maternal overweight and obesity, nulliparity, grandmultiparity, not being married and not being in paid work were independently associated with late stillbirth in multivariable analysis, whereas Pacific ethnicity was no longer significant (adjusted Odds Ratio 0.99; 0.51-1.91).
  
  
  CONCLUSIONS
  Pacific ethnicity was not found to be an independent risk factor for late stillbirth in this New Zealand study. The disparity in stillbirth rates between Pacific and European women can be attributed to confounding factors such as maternal obesity and high parity.
authors.affiliation: Department of Obstetrics and Gynaecology, University of Auckland, ACH Support Building, Park Road, Grafton, Auckland 1020, New Zealand. t.stacey@auckland.ac.nz
authors.forename: Tomasina
authors.initials: T
authors.lastname: Stacey
authors.forename: John M D
authors.initials: JM
authors.lastname: Thompson
authors.forename: Edwin A
authors.initials: EA
authors.lastname: Mitchell
authors.forename: Alec J
authors.initials: AJ
authors.lastname: Ekeroma
authors.forename: Jane M
authors.initials: JM
authors.lastname: Zuccollo
authors.forename: Lesley M E
authors.initials: LM
authors.lastname: McCowan
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D013287:Illicit Drugs / Q000009:adverse effects; D008423:Maternal Age; D015999:Multivariate Analysis; D009520:New Zealand / Q000453:epidemiology; D009765:Obesity / Q000150:complications*; D016017:Odds Ratio; D010298:Parity; D011247:Pregnancy; D011248:Pregnancy Complications / Q000208:ethnology*; D011263:Pregnancy Trimester, Third; D011446:Prospective Studies; D012307:Risk Factors; D012959:Socioeconomic Factors; D050497:Stillbirth / Q000208:ethnology*; D014028:Tobacco Smoke Pollution / Q000009:adverse effects; D044465:White People; D055815:Young Adult
chemical_list: D013287:Illicit Drugs; D014028:Tobacco Smoke Pollution