A twin pregnancy is a double blessing, but it can also carry greater risks than singleton pregnancies. In the U.S, about three in every 100 pregnant women give birth to twins or triplets. Twins are two offspring produced by the same pregnancy. Twins can be either monozygotic ("identical"), meaning that they develop from one zygote, which splits and forms two embryos, or dizygotic ("fraternal"), meaning that each twin develops from two different eggs and each egg is fertilized by its own sperm cell. In contrast, a fetus that develops alone in the womb is called a singleton, and the general term for one offspring of a multiple birth is multiple. Non-related look-alikes whose resemblance parallels that of twins are referred to as doppelgangers. . Mention your friends to see this Follow us @medshots for more shots