Offenbacher 2009.

Methods	Study design: RCT Location: USA Setting: Maternal Oral Therapy to Reduce Obstetric Risk (MOTOR) Study was a multicentre trial conducted at the Duke University Medical Center (and affiliated clinic at Lincoln Health Center), The University of Alabama at Birmingham Medical Center and 2 obstetric sites of the University of Texas Health Science Center at San Antonio, USA Recruitment period: December 2003 and October 2007
Participants	Inclusion criteria: pregnant women presenting for obstetric care of legal age (16 years) to consent and able to complete periodontal treatment before 23 6/7 weeks gestation; with at least 20 weeks and at least 3 periodontal sites with at least 3 mm of clinical attachment: before randomisation women could receive limited dental care to reduce the likelihood of an acute infectious event during pregnancy (including extraction of hopeless teeth and restoration of pulp‐threatening caries) Exclusion criteria: women with multiple gestation; history of human immunodeficiency virus infection, acquired immunodeficiency syndrome; autoimmune disease; or diabetes (women with gestational diabetes were eligible); need for antibiotic prophylaxis for periodontal probing or periodontal treatment; any obstetric finding that precluded enrolment in the study; women with advanced caries or advanced periodontal disease requiring multiple immediate extractions Mean age (± standard deviation (years)): Group A = 25.3 ± 5.5, Group B = 25.4 ± 5.5 Mean gestational age (± standard deviation (weeks)): Group A = 19.6 ± 2.2, Group B = 19.7 ± 2.1 History of preterm delivery: Group A = 9, Group B = 10.6 (P = 0.244) Number randomised: n = 1806 Number evaluated: n = 1806 (for preterm pregnancy < 37 weeks only). Attrition ranged from 21 to 119 depending on the outcome
Interventions	A) Antenatal periodontal treatment (n = 903 women randomised): received ≤ 4 sessions of supragingival and subgingival scaling and root planing (non‐surgical) using hand and ultrasonic instruments. Local anaesthesia was used as needed early in second trimester; plus full‐mouth polishing and oral hygiene home instructions B) Postnatal periodontal treatment (n = 903 women randomised): received periodontal care after delivery Treatment was administered by dental therapists
Outcomes	Gestational age < 37 weeks (including induced or spontaneous births, fetal demise, and miscarriage but not therapeutic abortions) [this primary outcome was originally specified as < 35 weeks]; gestational age < 35 weeks; birth weight; composite of neonatal morbidity before discharge; fetal demise after randomisation; neonatal death before discharge; respiratory distress syndrome; proven sepsis, intraventricular haemorrhage (IVH) III or IV; necrotizing enterocolitis (NEC); probing depth
Funding	Supported by National Institute of Dental and Craniofacial Research (NIDCR) grant U01‐DE014577 and National Center for Research Resources (NCRR) grants RR00046 and UL1RR025747
Notes	Before randomisation, women could receive limited dental care to reduce the likelihood of an acute infectious event during pregnancy including the extraction of hopeless teeth and restoration of pulp‐threatening caries. Sample size determination used data from the University of Alabama pilot trial and estimated a preterm (gestational age < 35 weeks) birth rate of 6% in the delayed periodontal therapy group compared with 2% in the periodontal therapy group. A sample size of 900 per treatment group would provide power of 91%, however, the primary outcome was changed due to advice from the monitoring board without change of sample size
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "A permuted block randomisation scheme with a random mixture of block sizes was used, stratifying participants by clinical center" Comment: although computer generation was not mentioned, we have judged the method of sequence generation to be adequate
Allocation concealment (selection bias)	Unclear risk	Not stated
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not feasible
Blinding of obstetric outcome assessment (detection bias)	Low risk	Quote: "Dental examiners were masked to treatment assignment of participants until after the postpartum examination, after the primary obstetric outcome was collected. Dental therapists were instructed not to divulge treatment status to study staff assigned to postnatal data collection. Participants and staff were instructed to not inform the postpartum examiner of the pregnancy outcome. The managing physicians were totally unaware of oral treatment assignments"
Incomplete outcome data (attrition bias) All outcomes	High risk	Attrition rates varied across outcome, ranged from 2.3% to 23% and was imbalanced for periodontal outcome, yet intention‐to‐treat analysis was only applied to the preterm pregnancy (< 37 weeks) outcome
Selective reporting (reporting bias)	Low risk	The authors changed the primary outcome from < 35 weeks to < 37 weeks gestational age, as recommended by the data and safety monitoring board. However, we considered this not to be a source of bias
Other bias	Unclear risk	Number of nulliparous pregnancies and alcohol use were higher in the treatment group compared to the control group, however, history of previous adverse pregnancy outcome was balanced between groups. Unclear whether this could be a source of bias