the relationship between maternal passive smoking during pregnancy and preterm delivery

background maternal passive smoking or exposure to environmental tobacco smoke may be a risk factor for maternal and newborn morbidity. objectives the current study aimed to assess the relationship between preterm delivery and tobacco smoke exposure in pregnant woman referring to the shabih-khani maternity hospital in kashan, iran. patients and methods an analytical retrospective cohort study was conducted on 300 non-smoker pregnant women in two groups of passive smoking and non- passive smoking. passive smoking was defined as exposed to smoking of 5 or more cigarettes per day during pregnancy at home. preterm delivery compared between passive smoking and non-passive smoking groups. results preterm delivery in the passive smoking group was more than non-passive smoking group (10% versus 6%, p = 0.2), this difference was not significant. gestational age was similar in the two groups (38.96 ± 1.56 and 38.99 ± 1.42 weeks in the passive and non-passive smoking groups respectively). conclusions preterm delivery in the exposed group was more than non-exposed group, but difference was not significant.