Passive maternal smoking and pregnancy outcome in a Saudi population

OBJECTIVE: A prospective study to investigate the effect of passive smoking on birth weight of infants born to women at the Department of Obstetrics and Gynecology, Security Forces Hospital, Riyadh, Kingdom of Saudi Arabia.

METHODS: The study group comprised of 868 singleton live births occurring during January to December 2001 at Security Forces Hospital, Riyadh, Kingdom of Saudi Arabia. Following delivery, mothers were asked for details of whether they smoked or used tobacco in any other form and if they had exposure to passive smoke at home or in the workplace. The daily exposure time to tobacco smoke was divided into 2 groups; up to 4 hours and 5-8 hours. Obstetric and medical details of the mothers were recorded from case notes, as were the details of the baby. Data was analyzed using Stat Pack Gold Statistical Analysis Package using Student t-test to compare discrete and continuous variables. Stepwise multiple regression analysis was performed to adjust the odds ratio from the influence of confounding factors.

RESULTS: Of the 868 women, 440 were passive smokers and 428 not exposed to tobacco smoke constituted the control group. Passive smokers were relatively younger with low parity and income. Passive smoking was significantly associated with a decrease in birth weight after adjusting for other factors (P=0.015) and an increase in the incidence of small for gestation age infants (P=0.0391). There was also no statistically significant difference in the birth weight between women exposed up to 4 hours of smoke and those exposed for 5-8 hours.

CONCLUSION: Passive maternal smoking was associated with a decrease in birth weight and an increase in small for gestation age infants. A dose-response relationship between passive maternal smoking and birth weight was not seen.