The Marcé Society is a multidisciplinary professional association dedicated to supporting research and assistance surrounding prenatal & post-partum mental health for mothers, fathers and their babies. The perinatal period is a very sensitive period for the women with psychological difficulties or psychiatric disorders but also for the foetus and the infant. Maternal treatment during pregnancy should take into account at the same time the mother’s health and the foetus health and development. The benefice and risk has to be considered for both. Results from a database from a multicentric national cohort study over thousand mother and infant inpatient joint admissions in France presented by Anne Laure Sutter-Dallay (past president of the Francophone group of the Marcé Society and secretary on the international Marcé Society) will bring important information to the discussion of the benefit /risk of maternal prenatal drug treatment for the infant. Dominique Dallay (member of the Marcé Society and executive member of the Francophone Marcé Society) will bring the obstetrician’s point of view on maternal treatment for addiction during pregnancy. Maria Luisa Imaz Gurrutxaga (member of the Spanish Marcé Society) will give information on the impact of the lithium treatment on the obstetrical and neonatal outcomes. The discussion will be open with the participants on this important question of benefice and risk to be considered at the same time for the mother’s improvement and child development but also for the early mother-child interaction and bonding support of early infant development and security.