title: Excessive crying at 3 months of age and behavioural problems at 4 years age: a prospective cohort study.
abstract: BACKGROUND
  Excessive crying in early infancy has been associated with behavioural problems among preschool children from high income countries but studies in low income and middle income countries are scarce.
  
  
  METHODS
  The 2004 Pelotas Birth Cohort is a population-based study planned to enrol all live births occurring in Pelotas that year and comprises 4231 children who so far have been followed up at 3, 12, 24, 48 and 72 months of age. Several familial, maternal and child characteristics were gathered in every follow-up. At the 3-month follow-up, infants whose mothers perceived them as crying more than others of the same age were classified as 'crying babies'. Child behavioural problems were assessed through the Child Behavior Checklist (CBCL) applied to the mother at the 48-month follow-up. Crude and adjusted ORs with 95% CIs were calculated by logistic regression.
  
  
  RESULTS
  Prevalence of excessive crying at 3 months was 11.9% (10.9% to 13.0%). Among children with excessive crying at 3 months the proportion in the clinical range for CBCL total, internalising and externalising problems at 4 years of age was 31.2%, 12.9% and 37.5%, respectively, against 20.6%, 6.8% and 29.6%, respectively, among non-crying babies. After controlling for confounders crying babies presented increased risk of being in clinical range of CBCL total (OR=1.34; 1.03 to 1.74), internalising (OR=1.55; 1.09 to 2.21) and externalising problems (OR=1.29; 1.01 to 1.64) than infants without excessive crying.
  
  
  CONCLUSIONS
  Excessive crying in early infancy may represent one important risk factor for developing behavioural problems in later phases of early childhood.
authors.affiliation: Post-graduate Program in Epidemiology, Department of Social Medicine, Faculty of Medicine, Federal University of Pelotas, Pelotas, Rio Grande do Sul, Brazil.
authors.forename: Iná S
authors.initials: IS
authors.lastname: Santos
authors.affiliation: Post-graduate Program in Epidemiology, Department of Social Medicine, Faculty of Medicine, Federal University of Pelotas, Pelotas, Rio Grande do Sul, Brazil Department of Preventive Medicine, School of Medicine, University of São Paulo, São Paulo, São Paulo, Brazil.
authors.forename: Alicia
authors.initials: A
authors.lastname: Matijasevich
authors.affiliation: Post-graduate Program in Epidemiology, Department of Social Medicine, Faculty of Medicine, Federal University of Pelotas, Pelotas, Rio Grande do Sul, Brazil.
authors.forename: Marcelo F
authors.initials: MF
authors.lastname: Capilheira
authors.affiliation: Post-graduate Program in Epidemiology, Department of Social Medicine, Faculty of Medicine, Federal University of Pelotas, Pelotas, Rio Grande do Sul, Brazil.
authors.forename: Luciana
authors.initials: L
authors.lastname: Anselmi
authors.affiliation: Post-graduate Program in Health and Behavior, Catholic University of Pelotas, Pelotas, Rio Grande do Sul, Brazil.
authors.forename: Fernando C
authors.initials: FC
authors.lastname: Barros
mesh_terms: D000293:Adolescent; D000328:Adult; D001938:Brazil / Q000453:epidemiology; D002653:Child Behavior Disorders / Q000453:epidemiology*; D002675:Child, Preschool; D003448:Crying; D004522:Educational Status; D005260:Female; D006801:Humans; D007223:Infant; D016015:Logistic Models; D017533:Marital Status; D008423:Maternal Age; D009035:Mothers / Q000523:psychology / Q000706:statistics & numerical data*; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology*; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors; D055815:Young Adult
keywords: CHILD HEALTH; Cohort studies; EPIDEMIOLOGY; PRIMARY HEALTH CARE; PUBLIC HEALTH