Smoke-free legislation and prematurity.

9.4 cigarettes/day) and 34% of them are exposed to second-hand smoke. In Argentina, the percentage of pregnant women who smoke (1520%) is one of the highest in the Americas and the world.3 Active and passive smoking during pregnancy causes low birth weight and preterm birth, among other harmful effects. All health care providers involved in the care of pregnant women are recommended to make a brief intervention towards smoking cessation at each antenatal care visit because it could be beneficial at any time during pregnancy. Individual cessat ion strategies (br ief intervention of health care providers) can be complemented with community strategies ( a d v e r t i s e m e n t r e g u l a t i o n , s m o k e f r e e environments), thus strengthening their efficacy. Results can be measured as an impact on individual health or as epidemiological indicators, such as smoking prevalence, exposure to second-hand smoke, or incidence of diseases directly related to smoking. In Scotland, the implementation of smoke-free environment laws led to a reduction in hospitalizations due to childhood asthma (Mackay D. et al. N Enl J Med 2010;363:1139-45) From an individual standpoint, only a few months are required to experience the benefits of smoking cessation on lung function and circulation. But five to fifteen years are required to have a reduction in the risk of stroke, coronary heart disease and cancer.5 In the study mentioned before, Cox et al. selected the pregnancy cycle, only 9 months long, to measure the impact of smoking cessation. The placenta is responsible for providing the energy necessary for fetal growth. In addition to its endocrinological functions, the placenta is basically an organ responsible for the circulation of nutrition and gas exchange. The placenta lives nine months, matures and declines at the end of pregnancy, or earlier if normal functioning is affected. All causes of circulation alterations affect the placenta and the developing fetus, and tobacco is one of the most harmful factors. Researchers found a reduction in preterm births with all the stages of implementation of smoke-free laws and a continuous descending trend in the years following the last stage. No reduction was found in the rate of children Smoke-free legislation and prematurity