The use of psychotropic medication in pregnant and breastfeeding women is an area of great challenge for both women with mental health problems and clinicians. There are many uncertainties regarding risks of untreated illness to mother, fetus or infant as well as concerns over potential risks to the fetus or infant associated with use of psychotropic medications during pregnancy or breastfeeding. The purpose of the British Association of Psychopharmacology guidelines is to provide advice regarding making decisions around treating mental illness in the perinatal period. This article provides a summary and explanation of the consensus guidance.