Creating a sense of urgency and provoking action - An example on the use of heat maps to address perinatal health inequalities.

Health outcomes of mothers and their (unborn) children in the perinatal period, i.e., during pregnancy and shortly after birth, can vary by geographical location. This is often due to differences in exposure to medical and social risk factors. Policies aimed at reducing inequalities in perinatal health can provide significant long-term health benefits, especially for (unborn) children. However, a lack of insight into regional perinatal health inequalities means that perinatal health is not always a priority in policy formulation. Novel methods should be used to draw attention to these inequalities, spark interdisciplinary debate and encourage collaborative initiatives. In this commentary, we propose that the development of heat maps that visualize perinatal health outcomes, and risk factors for those outcomes, could be a valuable tool in doing this. Heat maps are a data visualization technique that uses color variations to emphasize value differences between areas. Visualizing health inequalities could potentially create a sense of urgency among (local) stakeholders to initiate polices aimed at improving perinatal health. We illustrate the targeted use of heat maps with an example from the city of Rotterdam, the Netherlands. Large perinatal health inequalities between neighborhoods were visualized in heat maps by a team from the Erasmus Medical Center to bring these inequalities to the attention of the municipality of Rotterdam. Local collaborative initiatives were set up to reduce perinatal health inequalities. These local initiatives formed the foundation for later national policies, including proposals to online implement heat maps regarding perinatal health topics, that are still ongoing today.