American doctors say that mothers who smoke cigarettes before their babies are born may slow the growth of their babies’ lungs. They say reduced lung growth could cause the babies to suffer breathing problems and lung disease later in life. Doctors in Boston, Massachusetts studied 1 100 children. The mothers of some of the children smoked, the other mothers did not. Doctors found that the lungs of the children whose mothers smoked were 8% less developed than the lungs of the children whose mothers did not smoke, and that the children whose mothers smoked developed 20% more cold and br