摘要：Canada is undergoing an obesity epidemic and this complex problem creates challenges for reducing the public health burden. One emerging risk factor for the development of obesity in offspring is maternal smoking during pregnancy. (1) A recent meta-analysis found an increased relative risk of obesity in the offspring of 1.47 (95% CI: 1.26-1.73) where the mother had smoked during pregnancy. (1) However, to our knowledge, the population attributable risk (PAR) of smoking on obesity in the exposed child has not been calculated. Thus, to provide an estimate of the overall health impact of efforts to reduce smoking during pregnancy, we calculated the PAR for the United States, England and Canada.
Data from the major national health surveys or surveillance in each country were used to estimate smoking during pregnancy (US (2): smoking during the last three months of pregnancy, 12.3%; England (3): maternal smoking at the time of delivery, 11.5%; Canada (4): pregnant women aged 15-55 who smoked daily or occasionally during their previous pregnancy, 14.3%). We used Levin's formula ([P.sub.e] ([RR.sub.e] - 1)/[1 + [P.sub.e] ([RR.sub.e] - 1)]) to calculate PAR for each country.
The calculated PAR was 5.5% in the US, 5.1% in England and 6.3% in Canada. These estimates suggest that smoking during pregnancy is an avoidable risk factor responsible for a substantial proportion of the childhood obesity epidemic. For instance, this effect size implies that the health care costs associated with obesity in offspring as a result of their mothers' smoking during pregnancy are over $9 billion a year in the US alone. (5)
