Bianca Cox, from Hasselt University in Belgium, and colleagues examined the incidence of preterm delivery in the Belgian population after three phases of introduction of smoke-free legislation (in public places and most work places January 2006, in restaurants January 2007, and in bars serving food January 2010). The population comprised all 606,877 live born singletons (including 448,520 spontaneous deliveries) delivered at 24 to 44 weeks, from January 2002 to December 2011.

After the introduction of each phase of the smoking ban the researchers found that there were reductions in the risk of preterm birth. In the years or months before the ban there was no decreasing trend. A step change of −3.13 percent was observed in the risk of spontaneous preterm delivery on Jan. 1, 2007; after January 2010 there was an annual slope change of −2.65 percent. Similar results were seen in an analysis of all births. The results were not explained by personal, time-related, or population-related factors.

"Our study shows a consistent pattern of reduction in the risk of preterm delivery with successive population interventions to restrict smoking," the authors write. "This finding is not definitive but it supports the notion that smoking bans have public health benefits from early life."

Full Text