title: Quantifying the impact of deprivation on preterm births: a retrospective cohort study.
abstract: BACKGROUND
  Social deprivation is associated with higher rates of preterm birth and subsequent infant mortality. Our objective was to identify risk factors for preterm birth in the UK's largest maternity unit, with a particular focus on social deprivation, and related factors.
  
  
  RESULTS
  Retrospective cohort study of 39,873 women in Liverpool, UK, from 2002-2008. Singleton pregnancies were stratified into uncomplicated low risk pregnancies and a high risk group complicated by medical problems. Multiple logistic regression, and generalized additive models were used to explore the effect of covariates including area deprivation, smoking status, BMI, parity and ethnicity on the risk of preterm birth (34⁺⁰ weeks). In the low risk group, preterm birth rates increased with deprivation, reaching 1.6% (CI₉₅ 1.4 to 1.8) in the most deprived quintile; the unadjusted odds ratio comparing an individual in the most deprived quintile, to one in the least deprived quintile was 1.5 (CI₉₅ 1.2 to 1.9). Being underweight and smoking were both independently associated with preterm birth in the low risk group, and adjusting for these factors explained the association between deprivation and preterm birth. Preterm birth was five times more likely in the high risk group (RR 4.8 CI₉₅ 4.3 to 5.4), and there was no significant relationship with deprivation.
  
  
  CONCLUSIONS
  Deprivation has significant impact on preterm birth rates in low risk women. The relationship between low socio-economic status and preterm births appears to be related to low maternal weight and smoking in more deprived groups.
authors.affiliation: Department of Public Health and Policy, University of Liverpool, Liverpool, United Kingdom. dctr@liv.ac.uk
authors.forename: David
authors.initials: D
authors.lastname: Taylor-Robinson
authors.forename: Umber
authors.initials: U
authors.lastname: Agarwal
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Diggle
authors.forename: Mary Jane
authors.initials: MJ
authors.lastname: Platt
authors.forename: Bill
authors.initials: B
authors.lastname: Yoxall
authors.forename: Zarko
authors.initials: Z
authors.lastname: Alfirevic
mesh_terms: D005260:Female; D006801:Humans; D016015:Logistic Models; D008426:Maternal Deprivation; D016017:Odds Ratio; D011247:Pregnancy; D047928:Premature Birth / Q000453:epidemiology*; D012189:Retrospective Studies; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects; D012959:Socioeconomic Factors