Multiple Births

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Multiple Births Multiple births are rare in humans with twins as being the most common form of this event. Multiple births can arise in many different combinations of ways but the probability of giving birth to more than one child remains fairly constant when compared to the entire human race. The chances of multiple births can also vary from race and genetic background. Scientist and researchers do not know what the exact cause of these variations is but many of them feel that it is caused by hormone differences between different racial groups and/or the difference in social class. The prenatal and infant mortality is much higher in multiple pregnancies than in pregnancies that only involves one child. The danger of premature birth also increased with the higher number of offspring that are involved. In many multiple births, not all of the children survived to childhood or were born dead. Through the advances in technology, the survival rate of infants born in a multiple pregnancy has increased. The first quintuplets, five babies born in a single pregnancy, to survive in medical history were the Dionne quintuplets. The use of drugs that treat female sterility, or fertility drugs, may increase the chances of giving birth to multiple children. These drugs cause the ovaries to release an egg once a month but in some cases they release more than one egg, sometimes releasing several at a time, increasing the chances of a multiple birth. The drug clomiphene citrate is one of the most widely taken fertility drug and has resulted in the birth of twins about once in every twelve births, much greater than the chances of the birth of natural twins. Twins are the most common form of a multiple pregnancy. About one in eighty-seven births result in the birth of twins. Twins can be fraternal, also known as dizygotic twins, or identical, also called monozygotic twins, with the birth of identical twins being the rarest, occurring about four times in every thousand births, about one-forth as often as the birth of fraternal twins. This ratio of the birth of twins to the total number of births remains fairly constant but the birth of fraternal twins can alter greatly. Fraternal twins are most common among black African followed by people of European origin. Asian races originating from the orient are the least likely to give birth to fraternal twins. The birth of twins can occur in two different ways, the fertilization of a single egg or the fertilization of two eggs. In the case of dizygotic twins, the woman's ovaries release two eggs about the same time instead of one, with

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