We have found in this study that exposure to ETS in pregnant women was significantly associated with a higher risk of smallfor-gestation birth. Several epidemiological studies have shown similar effects. A meta-analysis of studies conducted before mid-1995 reported an overall RR of 1.2 (95 % CI, 1.1 to 1.3)
for LBW at term or small-for-gestational age among the infants born to mothers exposed to ETS during pregnancy. A recent small, case-control study found an association of IUGR with detectable nicotine level in mothers’ hair samples. With non-smoking women whose hair nicotine concentrations were in the lowest quartile as the reference group, the odds ratio(OR) for small-for-gestational-age birth was increased among women with concentrations in the upper and two middle quartiles (ORs 2.1, 95% CI=0.4 - 10.1 and 3.4, 95 % CI=1.3 - 8.6respectively).16 The reported results were not adjusted for confounders, although the authors stated that several potential confounders had no effect. There are some studies that have utilized urinary cotinine levels as a biomarker of exposure and found a higher risk of IUGR in babies born to mothers exposed to ETS.