All women planning to attend the antenatal clinics at King Edward Memorial Hospital (KEMH) in Perth, Western Australia are provided with written information about the trial with their appointment letter. Those attending other public antenatal clinics and a proportion of private practices also receive the information and invitation. Women who do not have exclusion criteria are invited by a research midwife to provide written informed consent to undergo a periodontal examination. After the examination those women who meet the criteria for periodontal disease are invited by a member of the research team to participate in the trial and to provide written informed consent to have treatment. A questionnaire is administered to obtain data on demographic and medical factors that may influence oral health and details of past and present dental care. Women who are found to not have periodontal disease are asked to provide consent for their obstetric outcomes to be retrieved from the state-wide computerized data collection system that encompasses all births in Western Australia.