Pregnancy and new motherhood may be crisis and vulnerability periods and therefore increase the risk of psychiatric disorders. Liaison psychiatry plays a major role in the first psychiatric evaluation of mothers in order to specify a diagnosis and to initiate a treatment when necessary. This article describes the care of mothers suffering from peripartum psychiatric disorders by the liaison psychiatry in the maternity ward, an outpatient practice, as well as an in-patient care unit where mother and baby can stay together. The multidisciplinary approach and its constellation around the mother-baby dyad are detailed and two clinical cases are reported.