Of 322 pregnant women with periodontal disease,
160 were randomly assigned to receive scaling and root planing
(SRP, cleaning above and below the gum line), plus oral hygiene
instruction, whereas the remaining 162 received only oral hygiene
instruction and served as an untreated control group. Subjects
received periodontal examinations before and 20 weeks after SRP,
and were classified blindly according to the results of treatment
into two groups: successful (‘non-exposure’) and unsuccessful
(‘exposure’) treatment. Groups were compared using standard
inferential statistics; dichotomous variables were compared using