Conjoined twins have fascinated people for centuries. They have been worshiped as gods and feared as monsters. They play a role in our myths and are marveled at in circus sideshows. Once called "monstrosities." Conjoined twins are increasingly accepted into our everyday lives as we grow to understand their usual physical and emotional bond and learn more about the science behind their development. (www. zygote).
The birth of two connected babies can be extremely traumatic and approximately 40-60% of these births are delivered stillborn with 35% surviving just one day. The overall survival rate of conjoined twins is somewhere between 5-25% and historical records over the past 500 years detail about 600 surviving sets of conjoined twins with more than 70% of those surviving pairs resulting in female twins. (www. twin stuff).
Conjoined twins is an extremely rare form of identical twins that occur perhaps in one out of every 75, 000 to 100, 000 births or 1 in 200 deliveries of identical twins, that of conjoined twins. (www. conjoined-twins). The ratio of 3: 1 show that they " re more female conjoined twins than male.
Conjoined twins are more likely to occur in Africa or India than China or the United States. This may be caused by any number of factors, being influenced by genetic and environmental conditions. It is presently thought that these factors are responsible for the failure of twins to separate after the 13 th day after fertilization. Conjoined twins artificially generated in amphibians by constricting the embryo so that two embryos form, one on each side of the constriction.
There are no documented cases of conjoined triplets or quadruplets. (www. multiples).