The perinatal period is a known time of increased vulnerability to mental health illnesses, which are associated with significant morbidity and mortality. The COVID-19 pandemic saw rates of perinatal mental illness increase, remaining elevated ever since. In this article, postnatal depression is considered a specific perinatal mental health illness, which demonstrates the unique challenges in defining and diagnosing perinatal mental illness, and mitigating the long-term consequences to the infant. As public health practitioners, midwives are effective in preventing postnatal depression, yet may be limited in their ability to support women because of service constraints. Key drivers in the UK are mandating the parity of esteem of mental health and the improved provision of perinatal services, with the recruitment and retention of a sufficient midwifery service highlighted as priority.