Abstract: Human pregnancy is an energetically demanding and socially embedded process that requires mothers to balance competing physiological needs while maintaining fetal development. In this talk, I integrate biocultural and mechanistic approaches to examine how social, ecological, and energetic environments become biologically embedded during gestation. Drawing on mixed-methods research with Latina women in the U.S., I show how neighborhood context, discrimination, and sociopolitical stress shape maternal psychological distress, and how support from allomothers buffers these effects. I then present evidence from immunological and placental biology indicating that maternal stress is linked to reductions in regulatory T cells and placental extracellular vesicles, revealing potential pathways through which social experience influences maternal-fetal communication and immune tolerance. Finally, I discuss findings from a project measuring total energy expenditure in pregnancy using doubly labeled water to test whether physical activity and psychosocial stress push gestation toward a metabolic ceiling. Together, this work highlights how social environments and energetic constraints jointly structure maternal-fetal trade-offs.