The inference of causality between smoking and low birth weight : Good science or good politics?

In excess of one billion dollars in damages has been claimed by litigants against the tobacco industry alleging that smoking by pregnant women causes low birth weight. The issue of smoking by pregnant women as a causal agent in clinically significant low weight births is examined with a sample of over 3,000,000 live births. In contrast to claims asserted by various litigants and an array of experts, smoking is found to have a complex, disordinal relationship to birth outcomes. The issue of inferring causality from purely correlational and related epidemiological data is confronted and cautions for the neuropsychological expert noted.