Passive smoking during pregnancy is associated with an increased risk of respiratory problems in infants

The European Respiratory Journal has published a study coordinated by Manolis Kogevinas, Joint Scientific Director and researcher at the Centre for Research in Environmental Epidemiology (CREAL), an allied ISGlobal centre. The study examined the association between maternal passive smoking during pregnancy and wheeze in children aged less than two years. The researchers found that the children of non-smoking mothers who were exposed to tobacco smoke during their pregnancy were 11% more likely to develop wheeze than unexposed children.

The study also found that the risk of respiratory symptoms was further increased by sustained exposure to smoke during the various phases of pregnancy and after birth. Thus, risk of wheeze increased by 29% in children exposed to passive smoke after birth in addition to their mother’s passive exposure during pregnancy. The highest risk was observed in the children of mothers who smoked actively during pregnancy, rising to 74% when the infant was also exposed passively after birth. Risk of wheeze was higher in children with an allergic family history.

Maternal smoking during pregnancy was known to increase the risk of childhood asthma, but the health effects on children of passive smoking on the part of the mother during pregnancy was previously unclear. This study, which included data on 27 993 mother-child pairs from 15 European birth cohorts, has shown that exposure to maternal passive smoking during pregnancy is an independent risk factor for wheeze in children up to 2 years of age.

"These findings have important implications for public health and indicate the need to protect pregnant women and small children from passive smoking by ensuring a smoke-free lifestyle,” explains Manolis Kogevinas. “To safeguard the health of their children, pregnant women should avoid both active and passive exposure to tobacco smoke,” he concludes.