title: The Auckland Stillbirth study, a case-control study exploring modifiable risk factors for third trimester stillbirth: methods and rationale.
abstract: BACKGROUND
  In high-income countries, stillbirth rates have been static in recent decades. Unexplained stillbirths account for up to 50% of these deaths.
  
  
  METHODS
  A case-control study was conducted in Auckland, New Zealand, from July 2006 to June 2009 to explore modifiable risk factors for late stillbirth (≥28 weeks of gestation). Eligible participants were women who had a singleton late stillbirth without a congenital abnormality. Two controls with ongoing pregnancies were randomly selected at the same gestation as each case. Data were collected through face-to-face interviews and from clinical records.
  
  
  RESULTS
  A total of 155/215 (72%) cases and 310/429 (72%) controls consented to take part in the study. Women who had a late stillbirth were more likely to be of Pacific ethnicity and of parity ≥4 (OR = 1.7, 95% CI: 1.1-2.6 and 2.7, 95% CI: 1.4-5.3, respectively). The median gestational age at diagnosis of fetal death was 261 days (IQR 239-279), and the median gestation at which the controls were interviewed was 264.5 days (IQR 240-274) P = 0.48. 'Unexplained antepartum death' (n = 61, 39.4%) and 'fetal growth restriction' (n = 29, 18.7%) accounted for almost 60% of stillbirths. The post-mortem rate for all cases was 47% (73/155) and 43% (26/61) for those classified as 'unexplained antepartum death'.
  
  
  CONCLUSIONS
  This study of risk factors for stillbirth is novel in that it used gestation-matched controls with ongoing pregnancies. Its detailed investigation into maternal health and behaviour during pregnancy has the potential to lead to a better understanding of modifiable risk factors for late stillbirth.
authors.affiliation: Department of Obstetrics and Gynaecology, University of Auckland, Auckland, 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; D005313:Fetal Death / Q000453:epidemiology; D005865:Gestational Age; D006801:Humans; D009520:New Zealand / Q000453:epidemiology; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D012307:Risk Factors; D050497:Stillbirth / Q000453:epidemiology*; D055815:Young Adult