title: No improvement in socioeconomic inequalities in birthweight and preterm birth over four decades: a population-based cohort study.
abstract: BACKGROUND
  Birthweight and gestational age are associated with socioeconomic deprivation, but the evidence in relation to temporal changes in these associations is sparse. We investigated changes in the associations between socioeconomic status (SES) and birthweight and gestational age in Newcastle upon Tyne, North of England, during 1961-2000.
  
  
  METHODS
  We used population-based data from hospital neonatal records on all singleton births to mothers resident in Newcastle (births with complete covariate information n = 113,182). We used linear regression to analyse the associations between neighbourhood SES and birthweight over the entire 40-year period and by decade, and logistic regression for associations with low birthweight (LBW) and preterm birth, adjusting for potential confounders.
  
  
  RESULTS
  There was a significant interaction between SES and decade of birth for birthweight (p = 0.028) and preterm birth (p < 0.001). Socioeconomic gradients were similar in each decade for birthweight outcomes, but for preterm birth, socioeconomic disparities were more evident in the later decades [for 1961-70, odds ratio (OR) was 1.1, 95% CI 0.9, 1.3, for the most deprived versus the least deprived quartile, while for 1991-2000, the corresponding OR was 1.5, 95% CI 1.3, 1.7]. In each decade, there was a significant decrease in birthweight adjusted for gestational age for the most deprived compared to the least deprived SES group [1961-1970: -113.4 g (95% CI-133.0, -93.8); 1991-2000: -97.5 g (95% CI-113.0, -82.0)], while there was a significant increase in birthweight in each SES group over time.
  
  
  CONCLUSIONS
  Socioeconomic inequalities did not narrow over the four decades for birthweight and widened for preterm birth. Mean birthweight adjusted for gestational age increased in all socioeconomic groups, suggesting an overall increase in fetal growth.
authors.affiliation: Institute of Health & Society, Newcastle University, Newcastle upon Tyne, England, UK. svetlana.glinianaia@ncl.ac.uk
authors.forename: Svetlana V
authors.initials: SV
authors.lastname: Glinianaia
authors.forename: Rakesh
authors.initials: R
authors.lastname: Ghosh
authors.forename: Judith
authors.initials: J
authors.lastname: Rankin
authors.forename: Mark S
authors.initials: MS
authors.lastname: Pearce
authors.forename: Louise
authors.initials: L
authors.lastname: Parker
authors.forename: Tanja
authors.initials: T
authors.lastname: Pless-Mulloli
mesh_terms: D000328:Adult; D015331:Cohort Studies; D015986:Confounding Factors, Epidemiologic; D004739:England / Q000453:epidemiology; D005260:Female; D005865:Gestational Age; D054624:Health Status Disparities; D006753:Hospital Records / Q000706:statistics & numerical data; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology; D047928:Premature Birth / Q000453:epidemiology* / Q000209:etiology; D012959:Socioeconomic Factors; D035862:Vulnerable Populations / Q000706:statistics & numerical data; D055815:Young Adult