During pregnancy, many changes take place in both systemic and local environments leading to a significant increase in the severity of gingivitis. In recent years, many studies have assessed the changes that occur within the gingival tissue during pregnancy and their potential impact on the foetus. Pregnancy is defined as a state that includes fertilization, implantation and embryonic and fetal growth that ends with the birth of a baby after 280 days or 40 weeks. Pregnancy gingivitis presents as gingival erythema, enlargement and bleeding. Epidemiological studies have shown that the prevalence of gingivitis increases during pregnancy when compared to control groups. The evidence indicates that hormonal changes affect the rate of cell turnover of the gingival tissues, inducing several microbiological changes in the subgingival flora and immunosuppression of the immune system. New evidence supports an association between the periodontal status and complications during pregnancy. Some countries have developed policies and practice guidelines that recommend oral care and the control of inflammation of the periodontal tissues throughout pregnancy. This chapter will review the effect of pregnancy on gingival status and the potential impact of gingival inflammation on the unborn child.