title: Biological determinants of spontaneous late preterm and early term birth: a retrospective cohort study.
abstract: OBJECTIVE
  Our aim was to examine the association between biological determinants of preterm birth (infection and inflammation, placental ischaemia and other hypoxia, diabetes mellitus, other) and spontaneous late preterm (34-36 weeks) and early term (37-38 weeks) birth.
  
  
  METHODS
  Retrospective cohort study.
  
  
  METHODS
  City of London and Middlesex County, Canada.
  
  
  METHODS
  Singleton live births, delivered at 34-41 weeks to London-Middlesex mothers following spontaneous labour.
  
  
  METHODS
  Data were obtained from a city-wide perinatal database on births between 2002 and 2011 (n = 17,678). Multivariable analyses used multinomial logistic regression.
  
  
  METHODS
  The outcome of interest was the occurrence of late preterm (34-36 weeks) and early term (37-38 weeks) birth, compared with full term birth (39-41 weeks).
  
  
  RESULTS
  After controlling for covariates, there were associations between infection and inflammation and late preterm birth (aOR = 2.07, 95% CI 1.65, 2.60); between placental ischaemia and other hypoxia and late preterm (aOR = 2.21, 95% CI 1.88, 2.61) and early term (aOR = 1.25, 95% CI 1.13, 1.39) birth; between diabetes mellitus and late preterm (aOR = 3.89, 95% CI 2.90, 5.21) and early term (aOR = 2.66, 95% CI 2.19, 3.23) birth; and between other biological determinants (polyhydramnios, oligohydramnios) and late preterm (aOR = 2.81, 95% CI 1.70, 4.64) and early term (aOR = 1.89, 95% CI 1.32, 2.70) birth.
  
  
  CONCLUSIONS
  Our findings show that delivery following spontaneous labour even close to full term may be a result of pathological processes. Because these biological determinants of preterm birth contribute to an adverse intrauterine environment, they have important implications for fetal and neonatal health.
authors.affiliation: Department of Epidemiology and Biostatistics, The University of Western Ontario, London, ON, Canada.
authors.forename: H K
authors.initials: HK
authors.lastname: Brown
authors.forename: K N
authors.initials: KN
authors.lastname: Speechley
authors.forename: J
authors.initials: J
authors.lastname: Macnab
authors.forename: R
authors.initials: R
authors.lastname: Natale
authors.forename: M K
authors.initials: MK
authors.lastname: Campbell
mesh_terms: D000293:Adolescent; D000328:Adult; D002170:Canada / Q000453:epidemiology; D005260:Female; D005865:Gestational Age; D006801:Humans; D000860:Hypoxia / Q000150:complications; D007231:Infant, Newborn; D007234:Infant, Premature; D007235:Infant, Premature, Diseases / Q000453:epidemiology / Q000209:etiology*; D007249:Inflammation / Q000150:complications; D016015:Logistic Models; D008875:Middle Aged; D010922:Placenta Diseases / Q000503:physiopathology; D011247:Pregnancy; D011256:Pregnancy Outcome; D047928:Premature Birth / Q000453:epidemiology / Q000209:etiology*; D012189:Retrospective Studies; D012959:Socioeconomic Factors
keywords: Obstetric labour; pregnancy complications; preterm birth; term birth