Postnatal depression (PND) is a significant public health concern that adversely affects the well-being, quality of life, and functional capacity of mothers. Occurring during the postnatal period, PND may present symptoms similar to major depression but can have more severe implications, including impaired self-esteem, reduced childcare abilities, and disruptions in familial roles. In severe cases, PND can lead to maternal or infant harm and negatively impact the mother–child relationship. Studies across different countries have reported varying prevalence rates of PND, ranging from 12% in England to 22.6% in Israel. In Nigeria, research with limited samples indicates prevalence rates between 14% and 29%, highlighting the magnitude of the problem within local contexts. Understanding the prevalence, risk factors, and impact of PND is crucial for informing clinical practices, guiding early interventions, and promoting maternal and child health outcomes. This study underscores the need for increased awareness among healthcare providers, particularly nurses and midwives, to ensure timely identification, support, and management of postnatal depression.