Mental health disorders are a serious public health issue with a largely unknown etiology. Developmental programming is the idea that genetic and environmental stimuli interact during fetal development to shape the individual and create an avenue for adverse outcomes. Animal and human studies can capitalize on this framework to study potential risk processes for neuropsychiatric disorders. Maternal inflammation, obesity, and diet are candidate risk factors for which prior studies have described a link with subsequent offspring disorders. However, how these affect specific aspects of behavior or brain development is unclear. The present work investigated this question in three studies using non-invasive imaging techniques in Japanese macaque and human subjects. Study 1 investigated how the maternal pro-inflammatory cytokine interleukin-6 (IL-6) may relate to Japanese macaque offspring amygdala volume development and anxiety-like behavior. Study 2 expanded on this and investigated how maternal IL-6, maternal diet, and offspring sex relate to cortical thickness development. Finally, Study 3 used patterns in macaque offspring functional connectivity to 1) make inferences about maternal levels of IL-6 and 2) translate the most significant models across species to make predictions in human infants from macaque functional connectivity.