Preterm birth occurring before 37 weeks gestation is associated with the majority of perinatal deaths world wide and almost half of long term neurological complications. In recent years, maternal periodontal disease has been identified as a risk factor but the pathophysiological basis for this association remains unclear. A recent trial [Michalowicz et al, New Eng J Med 335:1885, 2006] showed that treatment was safe and it improved periodontal disease but it failed to alter rates of preterm birth, low birth rate or fetal growth restriction when provided during pregnancy.

I agree with the authors of an editorial accompanying the above cited paper [Goldberg and Culhane, New Eng J Med 355:1925, 2006] that this relationship should be studied further. Given the huge burden of pre term births in many regions of the Developing World, clinical studies might be considered in one or more low income countries. Even if direct treatment of periodontal disease is convincingly shown not to reduce pre-term births, unraveling the pathophysiological basis for the association could suggest alternative strategies for reducing the persisting high rates of preterm birth.