Inflammation is a central feature and causal factor in common and serious disorders of reproduction and pregnancy that affect around 25% of couples or individuals seeking to have children. Infertility and recurrent miscarriage are increasingly prevalent conditions associated with a growing, multi-billion dollar reproductive medicine industry. Preeclampsia and preterm birth occur in ~20 million pregnancies each year and contribute substantially to the developmental origins of metabolic, neurocognitive and autoimmune/allergy diseases in children. Events around the time of conception that promote maternal adaptation to pregnancy and induce a state of adaptive immune tolerance are central to healthy embryo implantation, development of a robust placenta, optimal fetal growth and on-time birth. Insufficient tolerance, with elevated inflammatory mediators and leukocytes, is common to each of these conditions and contributes to the underlying pathophysiological processes. Regulatory T (Treg) cells are central mediators of pregnancy tolerance and direct other immune cells to counteract inflammation and promote robust placentation. Treg cells may therefore provide a tractable target for both preventative strategies and treatment interventions in preeclampsia. Interventions such as low dose IL-2 to boost Treg cell activity are under investigation for applications in pregnancy disorders. Other biologic and pharmacological interventions targeting Treg cells in autoimmune conditions also warrant evaluation. Emerging cell therapy tools involving in vitro Treg cell generation and/or expansion are also relevant. The success of preventative and therapeutic approaches will depend on resolving several challenges including developing informative diagnostic tests applicable before conception or during early pregnancy, selection of patient subgroups, and identifying appropriate windows for intervention. An over-riding challenge is insufficient pharmaceutical industry investment in developing novel pregnancy applications.