Bipolar disorder is associated with high morbidity and mortality. The management of bipolar disorder includes a broad approach involving psychoeducation, psychological therapies and psychotropic medication. The management of bipolar disorder in pregnancy is challenging; there is an increase in the rate of relapse of bipolar disorder in the perinatal period and treatment decisions are complex as clinicians are required to weigh up the risks of untreated illness versus unwanted treatment effects on both the mother and the developing fetus. Whilst depressive relapses are more common, women are also at an increased risk of postpartum psychosis, which is a psychiatric emergency that almost always requires inpatient treatment. This paper discusses the limited evidence base regarding the safety of psychotropic medication in the perinatal period, including challenges in perinatal mental health research and the lack of robust evidence. The general principles of prescribing in pregnancy, the importance of preconception counselling, and the risks and benefits associated with antipsychotics, mood stabilisers and antidepressants are addressed.