title: Decreasing incidence of placental abruption in Finland during 1980-2005.
abstract: OBJECTIVE
  To study the incidence trends of placental abruption.
  
  
  METHODS
  Register-based retrospective study.
  
  
  METHODS
  The Finnish Medical Birth Register and Hospital Discharge Register.
  
  
  METHODS
  A total of 6231 placental abruption cases among 1 576 051 deliveries.
  
  
  METHODS
  Data on demographic and pregnancy and delivery associated outcomes were collected. Data on overall incidence and maternal age were available 1980-2005. Data on other variables were available 1987-2005.
  
  
  METHODS
  Placental abruption
  
  
  RESULTS
  The overall incidence of placental abruption was 395/100 000 (0.4%). The incidence decreased 31%, from 487/100 000 in 1980 to 337/100 000 in 2005 (p < 0.001). The incidence was lowest among women aged 20-24 years (305/100 000) and highest among women aged ≥45 years (1309/100 000). During 1987-2005 the incidence was lowest among women with one or two deliveries (353/100 000) and highest in nulliparous women (382/100 000) and in women with three or more deliveries (595/100 000). The incidence was nearly double (577/100 000) among smoking compared with non-smoking women (341/100 000). The incidence was highest between gestational weeks 26 and 29. Among newborns weighing <1500 g the incidence was higher (5734/100 000) than among those weighing ≥2500 g (251/100 000). The incidence was higher in multiple (903/100 000) than in singleton pregnancies (374/100 000).
  
  
  CONCLUSIONS
  The incidence of placental abruption decreased during 1980-2005. The incidence was highest among women aged 45 years or more, multiparous and smoking women, in multiple pregnancies and in women with low birthweight newborns.
authors.affiliation: Department of Obstetrics and Gynecology, University Central Hospital, Helsinki, Finland. minna.tikkanen@hus.fi
authors.forename: Minna
authors.initials: M
authors.lastname: Tikkanen
authors.forename: Outi
authors.initials: O
authors.lastname: Riihimäki
authors.forename: Mika
authors.initials: M
authors.lastname: Gissler
authors.forename: Tiina
authors.initials: T
authors.lastname: Luukkaala
authors.forename: Marjo
authors.initials: M
authors.lastname: Metsäranta
authors.forename: Sture
authors.initials: S
authors.lastname: Andersson
authors.forename: Annukka
authors.initials: A
authors.lastname: Ritvanen
authors.forename: Jorma
authors.initials: J
authors.lastname: Paavonen
authors.forename: Mika
authors.initials: M
authors.lastname: Nuutila
mesh_terms: D000037:Abruptio Placentae / Q000453:epidemiology*; D000328:Adult; D017677:Age Distribution; D000367:Age Factors; D001724:Birth Weight; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D008875:Middle Aged; D010298:Parity; D011247:Pregnancy; D011272:Pregnancy, Multiple / Q000706:statistics & numerical data; D012042:Registries; D012189:Retrospective Studies; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects