title: A protocol to identify non-classical risk factors for preterm births: the Brazilian Ribeirão Preto and São Luís prenatal cohort (BRISA).
abstract: BACKGROUND
  Preterm birth is the main cause of morbidity and mortality during the perinatal period. Classical risk factors are held responsible for only 1/3 of preterm births and no current intervention has produced an appreciable reduction of this event. It is necessary to explore new hypotheses and mechanisms of causality by using an integrated approach, collaboration among research groups and less fragmented theoretical-methodological approaches in order to detect new risk factors and to formulate more effective intervention strategies.
  
  
  METHODS
  The study will be conducted on a convenience cohort of Brazilian pregnant women recruited at public and private prenatal health services. A total of 1500 pregnant women in São Luís, and 1500 in Ribeirão Preto, will be invited for an interview and for the collection of biological specimens from the 22nd to the 25th week of gestational age (GA). At the time of delivery they will be reinterviewed. GA will be determined using an algorithm based on two criteria: date of last menstruation (DLM) and obstetric ultrasound (OUS) performed at less than 20 weeks of GA. Illicit drug consumption during pregnancy will be determined using a self-applied questionnaire and the following instruments will be used: perceived stress scale, Beck anxiety scale, screening for depression of the Center of Epidemiological Studies (CES-D), experiences of racial discrimination, social network and social support scale of the Medical Outcomes Study and violence (Abuse Assessment Screening and violence questionnaire of the WHO). Bacterial vaginosis, urinary tract infection and periodontal disease will also be identified. Neuroendocrine, immunoinflammatory and medical intervention hypotheses will be tested. The occurrence of elective cesarean section in the absence of labor will be used as a marker of medical intervention.
  
  
  CONCLUSIONS
  Psychosocial, genetic and infectious mechanisms will be selected, since there are indications that they influence preterm birth (PTB). The studies will be conducted in two Brazilian cities with discrepant socioeconomic conditions. The expectation is to identify risk factors for PTB having a greater predictive power than classically studied factors. The final objective is to propose more effective interventions for the reduction of PTB, which, after being tested, might subsidize health policies.
authors.affiliation: Departamento de Saúde Pública, Universidade Federal do Maranhão (UFMA), Rua Barão de Itapary, 155 Centro, 65020-070 São Luís, Maranhão, Brasil. aasilva@ufma.br.
authors.forename: Antônio Augusto Moura
authors.initials: AA
authors.lastname: da Silva
authors.forename: Vanda Maria Ferreira
authors.initials: VM
authors.lastname: Simões
authors.forename: Marco Antonio
authors.initials: MA
authors.lastname: Barbieri
authors.forename: Viviane Cunha
authors.initials: VC
authors.lastname: Cardoso
authors.forename: Claudia Maria Coelho
authors.initials: CM
authors.lastname: Alves
authors.forename: Erika Bárbara Abreu Fonseca
authors.initials: EB
authors.lastname: Thomaz
authors.forename: Rejane Christine
authors.initials: RC
authors.lastname: de Sousa Queiroz
authors.forename: Ricardo Carvalho
authors.initials: RC
authors.lastname: Cavalli
authors.forename: Rosângela Fernandes Lucena
authors.initials: RF
authors.lastname: Batista
authors.forename: Heloísa
authors.initials: H
authors.lastname: Bettiol
mesh_terms: D001938:Brazil / Q000453:epidemiology; D002985:Clinical Protocols; D015331:Cohort Studies; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D007231:Infant, Newborn; D015337:Multicenter Studies as Topic; D018579:Patient Selection; D010510:Periodontal Diseases / Q000150:complications / Q000175:diagnosis; D011247:Pregnancy; D047928:Premature Birth / Q000453:epidemiology / Q000209:etiology*; D012107:Research Design; D012307:Risk Factors