López 2002.

Methods	Study design: RCT Location: Chile Setting: Consultorio Carol Urzua of Penalolen, a district of Santiago, Chile Recruitment period: recruited over a 20‐month period
Participants	Inclusion criteria: healthy pregnant women with periodontal disease (≥ 4 teeth with ≥ 1 sites with PD ≥ 4 mm and with CAL ≥ 3 mm at the same site) randomised, aged 18 to 35 years, singleton pregnancy, between 9 and 21 weeks gestation; with fewer than 18 natural teeth Exclusion criteria: history of congenital heart disease requiring prophylactic antibiotics for invasive procedures, existing diabetes before pregnancy, current use of corticosteroids, chronic renal disease, and the intention to give birth at another hospital Mean age (± standard deviation (years)): Group A = 28 ± 4.5, Group B = 27 ± 4.3 (P = 0.04) Mean gestational age (± standard deviation (weeks)): Group A = 39.6 ± 1.2; Group B = 39 ± 2 (P = 0.002) History of preterm low birth weight (%): Group A = 4.3, Group B = 7.4 (P = 0.21) Number randomised: n = 400 Number evaluated: n = 351 (attrition n = 49: loss to follow‐up n = 10, discontinuation of treatment n = 18, spontaneous abortion n = 14, indicated preterm delivery n = 7)
Interventions	1) Antenatal periodontal treatment (n = 200): plaque control instructions, scaling and root planing performed under local anaesthesia, each woman was instructed to rinse once a day with 0.12% chlorhexidine; periodontal therapy was completed before 28 weeks gestation and maintenance therapy was provided every 2 to 3 weeks until birth 2) Postnatal periodontal treatment (n = 200): monitoring every 4 to 6 weeks during pregnancy and treatment after birth All women: at study entry, all women received a full‐mouth periodontal examination and the following were determined: oral hygiene status, gingival inflammation, probing depth, clinical attachment level. Periodontal examination was given after 28 weeks of gestation. Carious lesions were treated and all teeth indicated for extraction were extracted from both groups No information on the expertise of the dental professional who administered intervention
Outcomes	Preterm birth < 37 weeks; low birth weight < 2500 g; preterm low birth weight; number of teeth after 28 weeks gestational age; % of sites with plaque; bleeding on probing; redness; probing depth, clinical attachment loss; after 28 weeks gestational age
Funding	Supported by project grant 1981094 Fondo de Investigación Científica y Tecnológica. Dental instruments partially provided by Hu‐Friedy Co. of Chicago Illinois
Notes	It was believed that 280 women in each group might detect a significant difference of preterm low birth weight between groups with a power of 80%. Data to determine the odds ratios for preterm birth, low birth weight and preterm low birth weight were analysed on an intention‐to‐treat basis. 29 women in the treatment group had severe aggressive periodontitis and were given metronidazole and amoxicillin (3 times daily) for 7 days in addition to mechanical treatment Antibiotics were always prescribed in women with severe periodontitis after they had completed at least 16 weeks of gestation
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Randomization was done equalizing periodontal disease as the relevant variable and probing depth was selected as the variable describing periodontal disease. Patients were assigned to 1 of 2 categories: those with a mean probing depth < 2.5 mm and those with a mean probing depth ≥ 2.5 mm. Patients were matched on the basis of the mean probing depth. Each patient of the matched pair was allocated to the treatment or the control group by a coin toss"
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	Labour and delivery management decisions were made by personnel who had no knowledge that the patients were participating a research study. The obstetrician who reviewed records of patients with preterm or low birth weight was masked from the mother's periodontal data
Incomplete outcome data (attrition bias) All outcomes	High risk	24/200 (12%) of women in the intervention group were lost to follow‐up (n = 6) or withdrew (n = 18); 4/200 (2%) in the control group were lost to follow‐up There was a difference in attrition rates between groups
Selective reporting (reporting bias)	Low risk	No apparent evidence of selective reporting
Other bias	High risk	The trial was stopped early due to benefit (preterm low birth weight) ‐ 400 women recruited from target sample size of 580, statistically significant difference in maternal and gestational age between groups