Women with single pregnancies at 12 to 20 weeks gestation with periodontal disease defined as periodontal pocketing at a threshold of 4mm or more at 10% or more of sites and who agree to receive periodontal treatment are eligible. The definition of periodontal disease is based on the published literature and our pilot study designed to determine the prevalence in our local obstetric population. Periodontal pocketing is used to define the presence of periodontal disease rather than clinical loss of attachment because it better represents the microbial challenge and is the most frequently employed criterion. In our pilot study, 15% of our general unselected population met this criterion.