Monochorionic twin pregnancies, characterized by a shared placenta and unique vascular architecture, face significantly elevated risks of perinatal complications compared to dichorionic and singleton pregnancies. This review examines the pathophysiology, cardiovascular, and neurological adaptations in three primary complications of monochorionic pregnancies: Twin-to-Twin Transfusion Syndrome (TTTS), Selective Fetal Growth Restriction (sFGR), and Twin Anemia Polycythemia Sequence (TAPS). TTTS disrupts hemodynamic balance, leading to distinct cardiac dysfunctions and increased neurodevelopmental injury (NDI). In sFGR, unequal placental sharing induces cardiovascular and neurological disparities between twins, while TAPS causes chronic anaemia and polycythemia with associated risks of brain injury. Advances in fetal therapy, such as fetoscopic laser surgery, have significantly improved survival, yet long-term sequelae remain concerning. This review emphasizes the importance of specialised prenatal care, multidisciplinary management, and comprehensive postnatal follow-up to mitigate adverse outcomes. The findings call for further research into the mechanisms of fetal adaptation and injury, aiming to refine diagnostic tools and therapeutic strategies.