title: Brazilian multicentre study on preterm birth (EMIP): prevalence and factors associated with spontaneous preterm birth.
abstract: BACKGROUND
  Preterm birth rate is increasing and is currently a worldwide concern. The purpose of this study was to estimate the prevalence of preterm birth in a sample of health facilities in Brazil and to identify the main risk factors associated with spontaneous preterm births.
  
  
  RESULTS
  This was a multicentre cross sectional study on preterm births in 20 referral obstetric hospitals with a case-control component to identify factors associated with spontaneous preterm birth. Surveillance was implemented at all centres to identify preterm births. For eligible consenting women, data were collected through a post-delivery questionnaire completed with information from all mother-newborn medical records until death or discharge or at a maximum of 60 days post-delivery, whichever came first. The risk of spontaneous preterm birth was estimated with OR and 95%CI for several predictors. A non-conditional logistic regression analysis was then performed to identify independently associated factors. The overall prevalence of preterm birth was 12.3%. Among them, 64.6% were spontaneous and 35.4% therapeutic. In the case-control component, 2,682 spontaneous preterm births were compared to a sample of 1,146 term births. Multivariate analyses identified the following as risk factors for spontaneous preterm birth among women with at least one previous birth: a previous preterm birth (ORadj = 3.19, 2.30-4.43), multiple pregnancy (ORadj = 29.06, 8.43-100.2), cervical insufficiency (ORadj = 2.93, 1.07-8.05), foetal malformation (ORadj = 2.63, 1.43-4.85), polyhydramnios (ORadj = 2.30, 1.17-4.54), vaginal bleeding (ORadj = 2.16, 1.50-3.11), and previous abortion (ORadj = 1.39, 1.08-1.78). High BMI (ORadj = 0.94, 0.91-0.97) and weight gain during gestation (ORadj = 0.92, 0.89-0.95) were found to be protective factors.
  
  
  CONCLUSIONS
  The preterm birth rate in these health facilities in Brazil is high and spontaneous preterm births account for two thirds of them. A better understanding of the factors associated with spontaneous preterm birth is of utmost importance for planning effective measures to reduce the burden of its increasing rates.
authors.affiliation: Department of Obstetrics and Gynaecology, School of Medical Sciences, University of Campinas, Campinas, Brazil.
authors.forename: Renato
authors.initials: R
authors.lastname: Passini
authors.affiliation: Department of Obstetrics and Gynaecology, School of Medical Sciences, University of Campinas, Campinas, Brazil; Centre for Studies in Reproductive Health of Campinas (CEMICAMP), Campinas, Brazil.
authors.forename: Jose G
authors.initials: JG
authors.lastname: Cecatti
authors.affiliation: Department of Obstetrics and Gynaecology, School of Medical Sciences, University of Campinas, Campinas, Brazil.
authors.forename: Giuliane J
authors.initials: GJ
authors.lastname: Lajos
authors.affiliation: Department of Obstetrics and Gynaecology, School of Medical Sciences, University of Campinas, Campinas, Brazil; Jundiai School of Medicine, Jundiaí, Brazil.
authors.forename: Ricardo P
authors.initials: RP
authors.lastname: Tedesco
authors.affiliation: Department of Obstetrics and Gynaecology, School of Medical Sciences, University of Campinas, Campinas, Brazil.
authors.forename: Marcelo L
authors.initials: ML
authors.lastname: Nomura
authors.affiliation: Department of Obstetrics and Gynaecology, School of Medical Sciences, University of Campinas, Campinas, Brazil.
authors.forename: Tabata Z
authors.initials: TZ
authors.lastname: Dias
authors.affiliation: Department of Obstetrics and Gynaecology, School of Medical Sciences, University of Campinas, Campinas, Brazil.
authors.forename: Samira M
authors.initials: SM
authors.lastname: Haddad
authors.affiliation: Department of Obstetrics and Gynaecology, School of Medical Sciences, University of Campinas, Campinas, Brazil.
authors.forename: Patricia M
authors.initials: PM
authors.lastname: Rehder
authors.affiliation: Department of Obstetrics and Gynaecology, School of Medical Sciences, University of Campinas, Campinas, Brazil.
authors.forename: Rodolfo C
authors.initials: RC
authors.lastname: Pacagnella
authors.affiliation: Department of Obstetrics and Gynaecology, School of Medical Sciences, University of Campinas, Campinas, Brazil.
authors.forename: Maria L
authors.initials: ML
authors.lastname: Costa
authors.affiliation: Centre for Studies in Reproductive Health of Campinas (CEMICAMP), Campinas, Brazil.
authors.forename: Maria H
authors.initials: MH
authors.lastname: Sousa
mesh_terms: D000028:Abortion, Induced / Q000009:adverse effects; D000328:Adult; D001938:Brazil / Q000453:epidemiology; D003430:Cross-Sectional Studies; D036861:Delivery, Obstetric / Q000009:adverse effects; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D011247:Pregnancy; D011248:Pregnancy Complications / Q000503:physiopathology; D011272:Pregnancy, Multiple / Q000502:physiology; D047928:Premature Birth / Q000453:epidemiology* / Q000209:etiology*; D015995:Prevalence; D012306:Risk; D012307:Risk Factors; D015430:Weight Gain / Q000502:physiology; D055815:Young Adult