There is an increasing amount of evidence suggesting a systemic link between periodontal disease in the pregnant mother and pre-term low birth weight (PLBW). Severe periodontitis affects at least 10% of the general population. The aetiology of periodontitis is essentially a bacterially induced inflammatory reaction within the attachment surrounding the teeth. Maternal infection has been linked with pre-term delivery. Normal pregnancy itself is associated with inflammatory changes very similar to those found in sepsis. Because the infected periodontal tissues can act as a reservoir for both bacterial products and inflammatory cytokines, it may be possible that periodontal infection and the resultant inflammation could be linked with PLBW. Current understanding suggests that prostaglandins and proinflammatory cytokines play a pivotal role in the initiation process because of the close relationship of inflammation and infection. High levels of maternally or fetally derived cytokines such as tumour necrosis factor alpha (TNFalpha) may enhance amniochorionic and decidual interleukin six (IL-6) expression. Prostaglandin E2 (PGE2) has also been associated with periodontitis and PLBW. Periodontitis is a possible risk factor for PLBW with an odds ratio of 2.30. For the majority of individuals affected with periodontitis, the condition is symptom-free until the disease is more advanced. Therefore there is the need for medical carers of pregnant patients to increase the awareness among pregnant women themselves. Although there is plenty of evidence associating periodontitis with PLBW, interventional studies for the treatment of periodontitis measuring the impact on PLBW are few in number. Therefore more good quality clinical trials are required to address this issue.