Infant birth weight as a measure of harm reduction during smoking cessation trials in pregnancy.

During pregnancy, a reduction of 50% or more of a biochemical measure of smoking, among continuing smokers, has been proposed by Windsor and colleagues as a new behavioral indicator of harm reduction because it was accompanied by greater infant birth weight compared with that of infants of smokers with lesser reductions. The purpose of the authors' study was to replicate these observations. During a trial of smoking cessation during pregnancy, data on cigarettes per day, urinary cotinine. and infant birth weight were obtained from 240 women. There were no significant differences in average birth weight between infants of women whocontinued to smoke but reduced their cigarette consumption by 50% or more and infants of women with lesser reductions. These results indicate that this birth weight comparison does not provide a valid estimate of the harm reduction associated with a reduction of 50% or more in cigarette consumption during pregnancy.