ABSTRACT
Background: There was strong evidence from studies conducted in developed countries that second-hand smoke (SHS) exposure is detrimental to the birth weight of newborn. This study was conducted to determine the effect of exposure to SHS smoke during pregnancy on the weight of newborns. Methods: A retrospective cohort study was conducted. The exposed group consists of 209 postnatal women who experienced SHS exposure at home because of a husband or other housemate who smoked inside the house throughout the pregnancy. The non-exposed group included 211 women who did not experience SHS exposure at home or at work during pregnancy. We excluded non-Malay ethnicity, multiple births, and congenital defects. Results: There was a significant difference in the adjusted mean birth weight between exposed infants [2893.0 g (95% confidence interval (CI): 2781.3, 3004.7)] and not exposed infants to SHS [3046.1 g (95% CI 2929.5, 3162.6) (P < 0.001)] after controlling for significant maternal factors. There was a 12.9 g (95% CI: 7.01, 18.96) reduction in birth weight for a corresponding increase in the exposure to the smoke of one cigarette (P < 0.001). The incidence of low birth weight (LBW) was higher in exposed women, [10% (95% CI: 5.94, 14.06)] compared to non-exposed women [4.7% (95% CI: 1.85, 7.55)]. Conclusions: This study found a significant association between SHS exposure during pregnancy and decreased birth weight.