Passive smoking during pregnancy

Non-smoking women exposed to other people’s tobacco smoke during pregnancy have lighter babies. Babies born to non-smoking women whose partners smoked weighed less than babies born to non-smoking couples. Moreover, women exposed to second-hand smoke in the workplace are also affected. Even relatively low-level exposure to tobacco smoke has a significant effect – exposure to second-hand smoke equivalent to one per cent of the dose inhaled by a smoker results in decreases in birth weight of 10 per cent of that seen in active smokers. The greater the amount of exposure, the greater the effect: in one UK study, babies born to women with the heaviest exposure to second-hand smoke were more than 70g lighter than
those in the least exposed group.

A recent review of the evidence concluded that on average, infants born to women exposed to second-hand smoke during pregnancy are 40–50g lighter than those born to women who are not exposed.
The reduction in birth-weight caused by passive smoking in pregnancy, while not of itself a risk for most babies, could compound health problems for those with additional health problems or risk factors.

Pregnant women exposed to other people’s tobacco smoke are about 20 per cent more likely to have a low birth-weight baby. There is some evidence to suggest that women who are exposed to second-hand smoke during their pregnancy are at increased risk of giving birth prematurely. For example, one study found that mothers ,exposed daily to second-hand smoke had a 23 per cent increased risk of giving birth prematurely.