A phenomenon of conjoined twins is extremely rare. Its occurrence is estimated to range from 1 in 49,000 births to 1 in 189,000 births. Surprisingly, a somewhat higher incidence takes place in some Asian and African countries. Approximately half of such twins are stillborn, but one-third of them die within 24 hours. Most live births are female, while most stillborns are male.

Anastasia and Tatiana Dogaru are Italian conjoined twins born on the 13th of January, 2004. They were scheduled to begin the first of several surgeries to separate them, however, the surgery was called off as too dangerous.