Before January 2019, no established solutions regarding the screening, assessment, and treatment of patients suffering from perinatal depression existed in Poland. From 2019, a new standard of perinatal care has imposed the obligation to monitor the mental state of women during pregnancy and in the postpartum period on the healthcare providers (mainly on midwives). Thus, our study aimed to evaluate midwives’ knowledge about prenatal and postnatal mental health disorders in the first six months of implementing the new standard of perinatal care in Poland.