Nearly half the US population will meet criteria for a neuropsychiatric disorder at some point in their lives, and 1 in 17 has a seriously debilitating illness. Although not all affected adults had an identified disorder as a child, increasingly these psychopathologies are conceptualized as the late-stage culmination of aberrant developmental processes shaped by a complex interplay of genes and experience, including experiences in utero. Decades of studies with pregnant animals demonstrate that stress-elicited perturbations in maternal biology affect offspring neurodevelopment. Studies of stress in pregnant women largely mirror these findings. Pregnant women with anxiety and/or depression experience greater life stress, and illness-related alterations in their neurobiology, with a potential to impact fetal neurobehavioral development via associated changes in the intrauterine environment and/or pharmacologic interventions. This article critically reviews findings on child development (including fetal neurobehavior) related to maternal depression, anxiety, and pharmacological treatments, primarily selective serotonin reuptake inhibitors (SSRIs). The hypothesis under review is that, in addition to genetics and characteristics of the postnatal environment, the familial transmission of risk for neuropsychiatric disorders involves a "third path"-prenatal exposure to psychiatric illness and its treatment.