Periodontal disease has been suggested to be an important risk factor for preterm low birthweight (PLBW). Here we report a case-control study of 236 cases (infants < 37 wks and weighing < 2499 g) and a daily random sample of 507 controls (> or = 38 wks and weighing > or = 2500 g). Clinical periodontal indices were measured on the labor wards. Associated risk factors for periodontal disease and PLBW were ascertained by means of a structured questionnaire and maternity notes. The risk for PLBW decreased with increasing pocket depth (odds ratio [OR] 0.83, 95% confidence interval [CI] 0.68 to 1.00). After adjustment for maternal age, ethnicity, maternal education, smoking, alcohol consumption, infections, and hypertension during pregnancy, this decreased further (OR 0.78, 95% CI 0.64 to 0.99). We found no evidence for an association between PLBW and periodontal disease. Our results do not support a specific drive to improve periodontal health of pregnant women as a means of improving pregnancy outcomes.

The influence of subject-based and environmental factors on the balance between the subgingival microbial challenge and the host response in periodontal diseases illustrates the intimate link between oral and systemic health. From this stems the hypothesis that the persistent Gram-negative challenge and associated inflammatory sequelae in periodontal disease may have consequences extending beyond the periodontal tissues themselves. This paper addresses the design of a case-control study to examine the relationship between preterm low birth weight (PLBW) and maternal periodontal disease. We present preliminary data on the prevalence of these 2 conditions in a group of mothers at the Royal Hospitals Trust, London, U.K. Cases are defined as mothers delivering an infant weighing less than 2,500g before 37 weeks gestation and controls as mothers delivering an infant of more than 2,500g after 38 weeks. We estimated that a study involving 800 mothers (1:3 case:control) should have sufficient power to detect an association with a minimum odds ration of 3 at the 5% significance level. Demographic details of 177 subjects demonstrated that they were representative of the local population, and the prevalence of PLBW was within the expected range. However, the extent and severity of periodontal disease were higher than predicted and may have reflected elevations in gingival inflammation associated with pregnancy. The final outcome of the study should help determine the need for further interventionist studies to demonstrate a causal relationship between periodontal disease and PLBW, as well as provide information on the prevalence of periodontal diseases in this study population.