Recurrent pregnancy loss (RPL) involves complex interactions between the maternal immune system and the developing fetus. Key immunological implications include immune tolerance, autoimmunity, inflammation, natural killer (NK) cell dysregulation, thrombophilia, and microbiota imbalance. Understanding these mechanisms informs fertility treatments, including immunomodulatory therapies, preconception screening for autoimmune and thrombophilic disorders, and personalized treatment approaches. Addressing immune dysregulation can improve pregnancy outcomes and support successful live births in RPL patients.