Multiple birth
From The Art and Popular Culture Encyclopedia
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A multiple birth occurs when more than one fetus result from a single pregnancy. The preceding pregnancy is called a multiple pregnancy. Different names for multiple births are used, depending on the number of offspring. Common multiples are two and three, known as twins and triplets, respectively. These and other multiple births occur to varying degrees in most animal species, although the term is most applicable to placental species.
Multiple birth siblings are either monozygotic or polyzygotic. The former result from a single fertilized egg or zygote splitting into two or more embryos (identical), each carrying the same genetic material (genes). Siblings created from one egg are commonly called identical. Since identical multiples share the same genetic material, they are always of the same sex. Polyzygotic (or fraternal) multiples instead result from multiple ova being ripened and released in the same menstrual cycle by a woman's ovaries, which are then fertilized to grow into multiples no more genetically alike than ordinary full siblings, sharing 50% of their genetic material. Multiples called "dizygotic" represent multiples from two eggs specifically. For example, a set of triplets may be composed of identical twins from one egg and a third non-identical sibling from a second egg.
The most common form of multiple births for humans is twins. Many placental species give birth to multiples as a matter of course, with the resulting group called a litter.
In the United States, it has been estimated that by 2011, 36% of twin births and 77% of triplet and higher-order births resulted from conception by assisted reproductive technology.
Cultural aspects
Certain cultures consider multiple births a portent of either good or evil.
Mayan culture saw twins as a blessing, and was fascinated by the idea of two bodies looking alike. The Mayans used to believe that twins were one soul that had fragmented.
In Ancient Rome, the legend of the twin brothers who founded the city (Romulus and Remus) made the birth of twin boys a blessing, while twin girls were seen as an unlucky burden, since both would have to be provided with an expensive dowry at about the same time.
In Greek mythology, fraternal twins Castor and Polydeuces, and Heracles and Iphicles, are sons of two different fathers. One of the twins (Polydeuces, Heracles) is the illegitimate son of the god Zeus; his brother is the son of their mother's mortal husband. A similar pair of twin sisters are Helen (of Troy) and Clytemnestra (who are also sisters of Castor and Polydeuces). The theme occurs in other mythologies as well, and is called superfecundation.
In certain medieval European chivalric romances, such as Marie de France's Le Fresne, a woman cites a multiple birth (often to a lower-class woman) as proof of adultery on her part; while this may reflect a widespread belief, it is invariably treated as malicious slander, to be justly punished by the accuser having a multiple birth of her own, and the events of the romance are triggered by her attempt to hide one or more of the children. A similar effect occurs in the Knight of the Swan romance, in the Beatrix variants of the Swan-Children; her taunt is punished by giving birth to seven children at once, and her wicked mother-in-law returns her taunt before exposing the children.
See also
- Biological reproduction
- Conjoined twins
- Half a Dozen Babies a 1999 drama film, about the 1993 born Dilley sextuplets.
- List of multiple births
- List of twins
- Only child
- Superfecundation (multiple pregnancy resulting from separate sexual intercourses)
- Twin
- Feodor Vassilyev
