Callen, D.F., Fernandez, H., Hull, Y.J., Svigos, J.M., Chambers, H.M., Sutherland, G.R.
A predominantly triploid 69,XXY placenta was found associated with a normal 46,XX infant. Therefore, a triploid placenta is apparently capable of supporting normal fetal development. The chromosome and pathological results support the conclusion that the triploid placenta originates from a ‘vanishing twin’ pregnancy. This case is unusual in that persistence of the placenta from the vanished twin has virtually replaced most of the normal placenta. Prenatal Diagnosis, Volume 11,437-442(1991)