title: Influence of maternal environmental tobacco smoke exposure assessed by hair nicotine levels on birth weight.
abstract: BACKGROUND
  While the perinatal outcomes of active maternal smoking are well documented, results of the effects of environmental tobacco smoke (ETS) exposure during pregnancy are inconsistent. We aimed to examine the effect of ETS exposure, assessed by maternal hair nicotine levels at 35th week of gestation, on birth weight and the risk of small for gestational age (SGA) and low birth weight (LBW).
  
  
  METHODS
  A total of 871 non-smoking healthy pregnant women were recruited by one Korean hospital between 1 October 2006 and 31 July 2007. Hair samples were collected and anthropometric questionnaires administered at 35th week of gestation. The primary outcome was birth weight and secondary outcomes were the risk of babies being SGA and LBW.
  
  
  RESULTS
  Log-transformed hair nicotine concentrations were inversely related with birth weight after adjusting for confounding variables (β=-0.077, p=0.037). After stratifying hair nicotine levels by tertiles (T1, low [0.0-0.28 ng/mg]; T2, medium [0.29-0.62 ng/mg]; and T3, high [0.63-5.99 ng/mg]), the mean birth weight in each groups were 3,342 g (T1) 3,296 g (T2) and 3,290 g (T3), respectively. However the difference between groups was not statistically significant by analysis of co-variance (ANCOVA) adjusting for covariates (p=0.062). In logistic regression analysis, the risk of SGA was higher in the T3 (OR=1.59, 95%CI 1.05-2.42) than in the reference group (T1), after controlling for confounding variables. The risk of low birth weight (<2,500 g, LBW) was not significantly higher (OR=1.44, 95%CI 0.95-2.19), but the risk of babies being below 3,000g birth weight was increased in the T3 group (OR=1.53, 95%CI 1.00-2.36) compared with that in the T1 group.
  
  
  CONCLUSIONS
  Maternal ETS exposure during pregnancy was inversely related with birth weight. The risk of SGA increased in the highest ETS exposure group compared with in the low exposure group. To prevent ETS exposure during pregnancy, more comprehensive tobacco control policies are needed.
authors: Department of Family Medicine, Sanbon Medical Center, Wonkwang University, College of Medicine, Gyeonggi-do, Republic of Korea E-mail : paek@hallym.or.kr, leewc@catholic.ac.kr.
authors: Jungun
authors: J
authors: Lee
authors: Dong-Ryul
authors: DR
authors: Lee
authors: Do-Hoon
authors: DH
authors: Lee
authors: Yu-Jin
authors: YJ
authors: Paek
authors: Won-Chul
authors: WC
authors: Lee
mesh_terms: D000328:Adult; D001724:Birth Weight / Q000187:drug effects*; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D005865:Gestational Age; D006197:Hair / Q000737:chemistry*; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D018811:Maternal Exposure / Q000009:adverse effects*; D009538:Nicotine / Q000378:metabolism*; D011247:Pregnancy; D018570:Risk Assessment; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*; D055815:Young Adult; D014026:Nicotiana
chemical_list: D014028:Tobacco Smoke Pollution; D009538:Nicotine