Since Belgium instituted a phased-in ban on smoking in public places, the Flanders region has seen a steady decline in preterm births, researchers report February 14 in BMJ. Smoking during pregnancy is known to impair fetal growth and shorten gestation, and some research suggests secondhand smoke can contribute to the same problems. But the effect of smoking bans on gestation is less clear. Belgium halted smoking in most public buildings in 2006, then extended the ban to restaurants in 2007 and to bars serving food in 2010. A research team led by Tim Nawrot at Belgium’s Hasselt University pored over health records and found a 3.1 percent decline in preterm births in 2007 and a further drop of 2.7 percent in 2010. The researchers accounted for other factors that might influence preterm births, such as the age of the mother, her national origin and even local air pollution. Earlier work has linked smoking bans to decreased heart attacks in Minnesota and less asthma in Scottish children.