title: Environmental tobacco smoke exposure and perinatal outcomes: a systematic review and meta-analyses.
abstract: BACKGROUND
  While active maternal tobacco smoking has well established adverse perinatal outcomes, the effects of passive maternal smoking, also called environmental tobacco exposure (ETS), are less well studied and less consistent.
  
  
  OBJECTIVE
  To determine to the effect of ETS on perinatal outcomes.
  
  
  METHODS
  Medline, EMBASE and reference lists were searched.
  
  
  METHODS
  Studies comparing ETS-exposed pregnant women with those unexposed which adequately addressed active maternal smoking.
  
  
  METHODS
  Two reviewers independently assessed titles, abstracts, full studies, extracted data and assessed quality. Dichotomous data were pooled using odds ratios (OR) and continuous data with weighted mean differences (WMD) using a random effects model.
  
  
  RESULTS
  Seventy-six articles were included with a total of 48,439 ETS-exposed women and 90,918 unexposed women. ETS-exposed infants weighed less [WMD -60 g, 95% confidence interval (CI) -80 to -39 g], with a trend towards increased low birthweight (LBW, < 2,500 g; RR 1.16; 95% CI 0.99-1.36), although the duration of gestation and preterm delivery were similar (WMD 0.02 weeks, 95% CI -0.09 to 0.12 weeks and RR 1.07; 95% CI 0.93-1.22). ETS-exposed infants had longer infant lengths (1.75 cm; 95% CI 1.37-2.12 cm), increased risks of congenital anomalies (OR 1.17; 95% CI 1.03-1.34) and a trend towards smaller head circumferences (-0.11 cm; 95% CI -0.22 to 0.01 cm).
  
  
  CONCLUSIONS
  ETS-exposed women have increased risks of infants with lower birthweight, congenital anomalies, longer lengths, and trends towards smaller head circumferences and LBW.
authors.affiliation: Department of Health Sciences, McMaster University, Hamilton, Ontario, Canada L8N 3Z5.
authors.forename: Giselle
authors.initials: G
authors.lastname: Salmasi
authors.affiliation: Department of Health Research Methodology, McMaster University, 1200 Main St. West, Hamilton, Ontario, Canada L8N 3Z5.
authors.forename: Rosheen
authors.initials: R
authors.lastname: Grady
authors.affiliation: Department of Health Sciences, McMaster University, Hamilton, Ontario, Canada L8N 3Z5.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Jones
authors.affiliation: Division of Maternal-Fetal Medicine, Departments of Obstetrics & Gynecology, Diagnostic Imaging, and Clinical Epidemiology & Biostatistics, McMaster University, 1200 Main St. West, Hamilton, Ontario, Canada L8N 3Z5.
authors.forename: Sarah D
authors.initials: SD
authors.lastname: McDonald
mesh_terms: D001827:Body Height; D002508:Cephalometry; D000013:Congenital Abnormalities; D005260:Female; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D018811:Maternal Exposure / Q000009:adverse effects*; D011247:Pregnancy; D012886:Skull / Q000033:anatomy & histology; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*
chemical_list: D014028:Tobacco Smoke Pollution