The hypothesis that periodontal disease is associated with pre-term low birthweight was tested in a prospective follow-up study of rural prima-gravida women (N = 227) who were free of tobacco, alcohol, and drug use. Women with 3rd trimester mean probing pocket depths, plaque, and bleeding scores that were greater than the median value in the cohort were defined as "exposed". There were 17 (7.5%) preterm low birthweight singleton deliveries in the cohort (among "exposed" = 12%; among "unexposed" = 5.6%; Odds Ratio = 2.3; 95% CI = 0.9-6.3). After adjustment for the independent variables, the OR for preterm low birthweight in relation to "exposure" was 1.9 (95% CI = 0.7-5.4). Our results are only suggestive of an association between periodontal disease and preterm low birthweight, perhaps indicating that previously reported associations may have been subjected to residual confounding due to tobacco, alcohol, and drug use.