title: Effect of psychosocial stress and physical activity on preterm birth: a cohort study.
abstract: OBJECTIVE
  To determine trimester-specific effects of risk factors for preterm birth (PTB).
  
  
  METHODS
  A prospective study was carried out in a district of Sri Lanka. A total of 885 pregnant mothers were recruited at equal to or less than 16 weeks of gestation and followed up until partus. Trimester-specific exposure statuses and potential confounding factors were gathered on average at the 12th, 28th, and 36th weeks of gestation. Physical activities were assessed by obtaining information about the duration of specific postures adopted per day by housewives during each trimester at home and both at home and during working hours for those who were engaged in paid employment. Psychosocial stress was assessed using the Modified Life Events Inventory and the General Health Questionnaire 30. Multiple logistic regression analysis was applied and the results were expressed as adjusted odds ratios (OR) and 95% confidence intervals (95%CI).
  
  
  RESULTS
  Standing equal to or less than 2.5 h/day during the first or second or both trimesters (OR 1.83, 95%CI 1.03, 3.25), maternal age of <25 years (OR 1.73, 95%CI 1.02, 2.95), education up to primary school level (OR 3.30, 95%CI 1.3, 8.36) and past history of low birthweight (OR 2.52, 95%CI 1.16, 5.48) were risk factors for PTB. Psychosocial stress was not found to be a risk factor for PTB.
  
  
  CONCLUSIONS
  Standing equal to or less than 2.5 h/day during the early trimesters was a risk factor for PTB among uncomplicated pregnancies. Further studies are recommended to assess the trimester-specific effect of psychosocial stress on PTB.
authors.affiliation: Department of Public Health, Faculty of Medicine, University of Kelaniya, Ragama. chrishantha-abeysena@mfac.kln.ac.lk
authors.forename: Chrishantha
authors.initials: C
authors.lastname: Abeysena
authors.forename: Pushpa
authors.initials: P
authors.lastname: Jayawardana
authors.forename: Rohini de A
authors.initials: Rde A
authors.lastname: Seneviratne
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D005865:Gestational Age; D006304:Health Status; D006801:Humans; D008423:Maternal Age; D009043:Motor Activity; D016017:Odds Ratio; D011247:Pregnancy; D047928:Premature Birth / Q000209:etiology*; D011446:Prospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013188:Sri Lanka; D013315:Stress, Psychological; D011795:Surveys and Questionnaires