Scaling and root planing is effective in reducing preterm birth only in high-risk groups.

Selection Criteria RCTs done in pregnant women who had periodontal disease (probing depth$4 mm or clinical attachment loss$2 mm in at least one site) where the intervention was SRP and at least one outcome was preterm birth (PTB # 37 weeks) were selected for the analysis. Studies were located by searching MEDLINE (1950-September, 2011), CINAHL (1980September, 2011), and EBSCO (1990-September 2011). Search was not limited to English language articles. Eleven foreign language studies were later eliminated, as they did not meet inclusion criteria. Hand searches were used to supplement the original search, and both obstetrics and periodontology experts were also contacted. Additional attempts were made to locate unpublished studies by searching ClinicalTrial.gov and by reviewing abstracts and specific conference proceedings. Twelve studies were included in the final analysis.