Mothers' Smoking May Harm Lungs of Unborn

A mother who smokes during pregnancy may impair the lungs of her unborn child, reports a study in the 19 October issue of The Lancet. In the past, some experts--including those in the tobacco industry--had challenged studies linking children's lung problems with maternal smoking habits. But pediatric researchers say this report confirms the effect.

The new finding comes from a group led by S. M. Stick of the Princess Margaret Hospital for Children in Perth, Australia. He and his colleagues set out to measure the respiratory function of infants during the first hours of life outside the womb. By testing children immediately after birth, they hoped to answer critics who had said that postnatal exposure to smoke or infectious agents--not lung function itself--was the cause of infants' wheezing and other lung problems. A key innovation in this study was Stick's use of a high-tech device to measure the volume of breath--a plethysmograph, worn like a belt around the chest. It avoids the need for a face mask, which often requires sedation and may alter breathing.

Stick and his team examined 461 infants born to mothers enrolled in a large pregnancy study. They also asked the mothers how much they smoked and checked their blood for cotinine, a metabolite of tobacco smoke. They found that a distinctive shallow breathing pattern in infants was linked independently to three risk factors: If their mothers suffered from hypertension, had a family history of asthma, or smoked at least 10 cigarettes a day. Because older children with obstructive lung disease have exhibited a similar breathing pattern, Stick theorized that the infants' lungs had developed poorly.

``The picture is very clear,'' claims pediatric pulmonologist Fernando Martinez of the University of Arizona, Tucson. ``Smoking is not only bad for the moms who smoke during pregnancy, but it is also very bad for the children. This is something ... the tobacco industry can no longer argue against.''