Role of oxidative injury in affecting the foetal & placental weights on exposure to tobacco smoke.

Objective: To investigate the role of oxidative injury in affecting foetal and placental weights in mice by exposing them to tobacco smoke with or without supplementation with antioxidants.

Methods: The randomized control trial of pregnant mice at day one of gestation was conducted at Anatomy Department CPSP Regional Center Islamabad, from March 2005 to October 2005. The mice were divided into three groups: Group C had controls, while the two other groups, groups S and SV were exposed to secondary tobacco smoke in a whole body exposure chamber with and without supplementation with vitamins respectively. At term, the animals were sacrificed and the placentae and foetuses were weighed. The average values were calculated. The means for each group were analysed and the foetal placental ratio was calculated. SPSS 17 was used for statistical analysis.

Results: There were 44 mice; 15(34%) each in S and SV groups, while Group C had 14(32%) mice who acted as the controls. The mean foetal weight in Group S was 0.65±0.52g which was significantly less (p<0.0001) than1.48±0.19g in Group C. The mean foetal weight in Group SV was 0.97±0.65g which was not significantly different from S (p=0.124). The mean placental weight in Group S was 0.16±0.02g which was significantly less than 0.21±0.05gin Group C (p=0.014). In Group SV it was significantly more than Group S (p<0.0001). The ratio of mean foetal and mean placental weights in the groups C, S and SV were 7.05, 3.92 and4.41 respectively.

Conclusions: Prenatal exposure to tobacco smoke decreased the mean foetal and placental weights and the foetal-placental ratio. This may partly be attributed to oxidative injury induced by free radicals in the tobacco smoke as it is prevented to some extent by simultaneous administration of antioxidants.