Original
Lack of amniotic fluid in an amniotic, or too much in the other ( mono-di twins). A "stuck" position of one of the babies. Early size discrepancy between the two babies. Bladder not having fluid in the "stuck" baby. Enlarged or thick walls of the heart ( cardiomyapothy). Lack of blood flow in the umbilical cord, and lack of flow in the ductus venosis for the smaller baby, and increased amounts in the other baby.