From the moment we take our first breath, brainstem networks that drive rhythmic breathing behavior and ventilatory chemoreflexes must be sufficiently developed to support life. Specific nuclei in the brainstem medulla develop rapidly to meet this demand, but are still nascent and vulnerable to biological stress during early postnatal development. Developmental perturbations, such as being born preterm, or infection, can be particularly destabilizing in the infant and may result in cardiorespiratory failure. This project leverages single-cell transcriptomics as a means of defining the developmental trajectory of brain cells which produce breathing motor rhythms and respond to changes in the environment. By following the development of these cell populations through the perinatal stage of development and after inflammatory challenge, we aim to clarify the mechanisms underlying respiratory dysfunction in infants.