Pregnancy complications, especially low birth weight (defined as birth weight less than 2.500 kilograms (kg)), pre-term delivery (less than 37 weeks) and pre-ecclampsia (elevated maternal blood pressure), continue to be a significant public health issue in both developed and developing countries. Recent data indicate that periodontal disease might confer risk for several systemic disorders. The relationship between periodontal diseases in pregnancy and obstetric complications has been increasingly investigated, showing inconclusive results. The purpose of this study is to review the current literature regarding the influence of periodontal status on pregnancy outcome, including the effect of periodontal treatment. Further research in this area is required, particularly with respect to the effect of population differences on this potential association between periodontal diseases and pregnancy complications as well as on the exact mechanism of this association. Since pregnancy tends to influence periodontal status, and considering the potential reported relation between periodontal disease and pregnancy complications, careful periodontal diagnosis and treatment before as well as during pregnancy is warranted.