The authors of one RCT demonstrated that deep root scaling reduced the risk of birth before 37 weeks’ gestation (preterm birth),with a risk reduction of 0.5 (confidence interval [CI], 0.2 to 1.3). For birth before35 weeks’ gestation (very preterm birth), the risk reduction was 0.2 (CI, 0.02 to 1.4) for women with periodontitis.