title: Maternal risk of ischaemic heart disease following elective and spontaneous pre-term delivery: retrospective cohort study of 750 350 singleton pregnancies.
abstract: BACKGROUND
  Previous studies have demonstrated an overall association between pre-term delivery and maternal risk of subsequent ischaemic heart disease (IHD). The underlying mechanism is unknown. We explored whether the association was specific to spontaneous or elective pre-term delivery.
  
  
  METHODS
  We linked three Scottish routine data sources. The Scottish Morbidity Record 1 collects data on all acute hospital admissions, Scottish Morbidity Record 2 collects data on all pregnancies and Scotland's Registrar General collates data from all death certificates. Cox proportional hazards models were used to explore associations between pre-term delivery and subsequent IHD events (fatal and non-fatal) and IHD deaths. Analysis was restricted to women aged between 35 and 65 years at either the time of their first IHD event or at the end of follow-up.
  
  
  RESULTS
  The cohort comprised 750,350 women who delivered a live, singleton infant following their first pregnancy. We demonstrated independent associations between pre-term delivery and IHD death [hazards ratio (HR) 2.26, 95% confidence interval (CI) 1.88-2.71] and total IHD events (HR 1.58, 95% CI 1.47-1.71). Associations were greater for elective than spontaneous pre-term delivery (P = 0.005). There was a trend whereby the association between pre-term delivery and IHD increased with decreasing age at first event.
  
  
  CONCLUSIONS
  We observed a stronger association between elective pre-term delivery and IHD, than spontaneous pre-term delivery and IHD. Elective pre-term delivery is usually undertaken because of growth restriction or pre-eclampsia, resulting from placental dysfunction. The age trend observed suggests an underlying genetic predisposition to both placental dysfunction and IHD.
authors.affiliation: British Heart Foundation Cardiovascular Research Centre, University of Glasgow, UK.
authors.forename: Claire E
authors.initials: CE
authors.lastname: Hastie
authors.forename: Gordon C S
authors.initials: GC
authors.lastname: Smith
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Mackay
authors.forename: Jill P
authors.initials: JP
authors.lastname: Pell
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D005260:Female; D006801:Humans; D007751:Labor, Induced / Q000706:statistics & numerical data*; D007743:Labor, Obstetric; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000453:epidemiology* / Q000209:etiology*; D010298:Parity; D011247:Pregnancy; D047928:Premature Birth; D016016:Proportional Hazards Models; D012042:Registries; D012189:Retrospective Studies; D012307:Risk Factors; D012606:Scotland / Q000453:epidemiology