Prenatal maternal infections are a potentially preventable risk factor, providing the opportunity to influence policy decisions around the prevention of maternal infection, provision of treatment and follow-up support after birth. Examining how maternal mental health may affect the relationship between infections and development will provide important information and guidance for health care practitioners in the fields of pre- and perinatal care. This work will also directly focus on the outcomes for children affected by prenatal maternal infections and mental health issues from areas with varying levels of deprivation, and help to guide policy and healthcare interventions to address inequalities. Findings will help to ensure the best possible start in life. Findings are expected to be of international interest. This work would be pivotal in helping to bridge a significant gap in our current understanding, which is limited to our knowledge from studies where hospital records are linked to diagnosis registers, where it is not possible to connect individual infection responses to specific behavioural outcomes in children.