Tag Archives: preterm birth

Smoke-free legislation associated with better child and perinatal health

Clinical Question:  How much does smoke-free legislation impact the health of children?

The passage of smoke-free legislation is associated with nearly immediate and meaningful improvements in the number of preterm births and asthma exacerbations. (LOE = 1a)Bottom Line


Been JV, Nurmatov UB, Cox B, Nawrot TS, van Schayck CP, Sheikh A. Effect of smoke-free legislation on perinatal and child health: a systematic review and meta-analysis. Lancet 2014;383(9928):1549-1560.

Study DesignMeta-analysis (randomized controlled trials)


SettingVarious (meta-analysis)



These authors searched many databases, including trials registries, to identify published and unpublished studies that evaluated the effects of smoke-free legislation on preterm birth, low birth weight, and asthma. Ultimately they included 11 studies (5 North American and 6 European) with more than 2.5 million births and nearly a quarter million asthma exacerbations! Nearly all the legislation required comprehensive and immediate changes (as opposed to the step-wise implementation used in Belgium). Four studies were deemed to have low risk of bias, 6 had moderate risk, and 1 had high risk. The higher-quality studies tended to be from Europe and the legislations invoked national-level bans on tobacco use. In 4 studies with nearly 1.4 million births, smoke-free legislation was associated with a 10% relative decrease in the frequency of preterm birth immediately after the legislation, and that result was maintained. However, the legislation had no impact on the frequency of low-birth-weight infants (6 studies with nearly 2 million participants). In 3 studies with more than 240,000 events, legislation was associated with an immediate 10% drop in the rate of hospital attendance for asthma exacerbations. There was no statistically significant subsequent decline, though. The authors provide additional data on secondary outcomes, such as small for gestational age, birth defects, and so forth, most of which were inconsistently studied and showed inconsistent results.

Henry C. Barry, MD, MS
Michigan State University
East Lansing, MI