A review of the literature demonstrates that the incidence of new mental disorders and their prevalence during pregnancy is similar to the 12-month incidence of mental disorders in women during other periods of their lives. The prevalence of severe mood, behavior, and cognitive symptoms during pregnancy is rather high. Severe mental symptoms during pregnancy have been reported to be associated with an increased rate of complications during pregnancy and delivery, preterm deliveries, low birth weight, a higher rate of postpartum depression, and a longer-term impact on the offspring's development. Several pre-pregnancy risk factors to develop dysphoric symptoms have been reported, but their utility for primiparous women with no previous history of mental disorders is unclear. The association of mental symptoms with general symptoms and biological changes during pregnancy is also unclear. Given the short- and long-term impact of dysphoric symptoms and stress during pregnancy on mother and child, efficacious, efficient, and safe prevention and treatment modalities are essential and achievable. Clarification of the nature and phenotyping of mental and general symptoms during pregnancy is an important step for the development of effective interventions.