Rush, D. and E. H. Kass (Channing Laboratory, Boston City Hospital, Boston, Mass. 02118). Maternal smoking: a reassessment of the association with perinatal mortality. Am J Epidemiol 96: 183–196, 1972.—A total of 1, 020 women were studied prospectively during pregnancy, and many differences between smokers and nonsmokers, and whites and blacks, were found. Smokers and blacks had infants of lower birth weight; the latter also had appreciably shorter gestations. An additional 2, 256 women were studied in an assessment of perinatal mortality. Black smokers had an 86% excess mortality over nonsmokers; among whites, the excess was 11%. The English language literature was reviewed, and reports of 12, 388 perinatal deaths and abortions were found. Smokers had an excess perinatal loss of 34.4%. Where reported, excess loss was higher among the poor, or among blacks. Prudence dictates that smoking be considered a risk factor in pregnancy, until controlled trials of the effects of discontinuing smoking can be undertaken.