Twin-to-twin transfusion syndrome Overview Most pregnancies result in one baby. In about one in 80 pregnancies, twins are conceived. This can occur in one of two ways: The more common way (which accounts for two-thirds of cases) is for the two different sperm to fertilize two different eggs, resulting in what is called a dizygotic (DZ) twin gestation. These twins are often called fraternal twins. In this type of twinning each tw.. 2014. 12. 11. 이전 1 다음