Depression during pregnancy is common, affecting an estimated 20% of women. However, conflicting data exist concerning the outcomes of this disorder. Thus, we reviewed studies that presented evidence for the use of antidepressants and those that examined untreated depression during the gestational period, in terms of clinical and epidemiological aspects.Observational studies have provided reassuring evidence of the safety of antidepressant use during pregnancy. However, due to the reluctance of healthcare providers to prescribe and patients to take medication during the obstetric period, approximately three-quarters of those diagnosed with depression remain untreated. Furthermore, healthcare providers apparently do not recognise the disorder in up to 50% of pregnant women who experience depression. Increased antidepressant dosing during pregnancy may be required to maintain euthymia; however, guidelines for effective dosing levels are absent. Consequently, many patients remain inadequately treated. Substantial maternal and fetal morbidity including substance abuse, functional impairment, increased risk of postnatal depression, and poor pregnancy outcomes have resulted from untreated depression.The consequences of those outcomes are likely to be associated with substantial clinical, social and economic burdens. An incidence-based assessment of the consequences of prenatal depression would be useful in order to: (i) establish the impact on the quality of life of these patients and their families; (ii) assess the associated economic burden on individual families and the healthcare system; and (iii) to provide epidemiological data to enable the provision of suitable management strategies for these patients.