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A multiple birth occurs where more than one fetus exits the womb in a single pregnancy. Different names for multiple birth are used, depending on the actual multiple. Common multiples are two and three, known as twins and triplets respectively. Twins, triplets and other multiple births occur to varying degrees in most animal species, although the term is most applicable to placental species.
There are two common types of multiple births, fraternal (dizygotic) and identical (monozygotic). Identical siblings arise where one egg is fertilised and the resulting zygote splits into more than one embryo. Identical siblings therefore have the same genetic material. Fraternal siblings result from the fertilisation and implantation of more than one egg, so fraternal siblings are not genetically identical, and instead have an analogous genetic similarity of any brothers and sisters.
A very rare third type of twinning is now believed to occur when an unfertilized ovum splits into two equal parts prior to fertilization, creating a second complete ovum, called the "polar body". After splitting, both ovum are each then fertilized by different sperm. This results in twins who share half their genes in common (from the mother) and the other half different (from the two sperm). Polar body twins share about 75% of their genetic markers, less than identical twins but more than fraternal twins. They share some features of identical twins and some features of fraternal twins and are so-called half-identical twins. However, DNA-based zygosity tests are currently not available to determine if twins are polar-body twins.
The most common form of human multiple birth is twins (two babies), but the typical order of multiple births in other placental species differs dramatically. Some species give birth to multiple offspring as a matter of course and the resulting group of offspring is called a litter.
- Monozygotic — multiple (typically two) foetuses produced by the splitting of a single zygote
- Dizygotic — multiple (typically two) foetuses produced by two zygotes
- Polyzygotic — multiple foetuses produced by two or more zygotes
- Litter — the offspring produced by a multiple birth in non-human placentals.
Terms used for the order of multiple births are largely derived from the Latin names for numbers.
- Two offspring — twins
- Three offspring — triplets
- Four offspring — quadruplets
- Five offspring — quintuplets
- Six offspring — sextuplets
- Seven offspring — septuplets
- Eight offspring — octuplets
- Nine offspring — nonuplets
- Ten offspring — decaplets
- Eleven offspring — undecaplets
- Twelve offspring — duodecaplets
- Thirteen offspring — tredecaplets
- Fourteen offspring — quattuordecaplets
- Fifteen offspring — quindecaplets
Higher order multiples
High orders of multiple births (three or more offspring in one birth) may result in a combination of fraternal (genetically different) and identical (genetically identical) siblings. The latter are occasionally given the term of super twins. For example, a set of quadruplets may consist of two sets of identical twins. In such a case each child has one identical and two fraternal siblings. Identical triplets or quadruplets are very rare, as this means that the original egg split and then either one of those split off sections split again (producing identical triplets) or, even more rare, both of the split off sections split again (producing identical quadruplets). Some times the original egg will split twice (to produce four embryos), and either all four survive and produce quadruplets, or one of the embryos does not survive and results in identical triplets.
Human multiple births
The most common form of human multiple birth is twins (two babies), but cases of higher orders up to octuplets (eight babies) have all been recorded with all siblings being born alive. The largest set in which all members survived more than a few days is septuplets, the first of which was in 1997. The largest set to have even a single member survive is octuplets, in 1998 (with the seven surviving octuplets born in Texas).
There have been a few sets of nonuplets (nine) in which a few babies were born alive, though none lived longer than a few days. There have been cases of human pregnancy which started out with ten, eleven, twelve and fifteen fetuses, but no known instances of live births of such high multiples in a single pregnancy. Most of these pregnancies are a result of fertility medications, though a set of duodecaplets (twelve) was conceived spontaneously (without the aid of fertility treatments) in Argentina in 1992.
Multiple pregnancies in humans are usually delivered before the full term of 40 weeks gestation. The average length of pregnancy is around 36 weeks for twins, 34 weeks for triplets and 32 weeks for quadruplets.
Causes and frequency
Human multiple births can occur either naturally (the woman ovulates multiple eggs or the fertilized egg splits into two) or as the result of infertility treatments such as IVF (several embryos are usually implanted to compensate for their lower viability) or fertility drugs (which can induce multiple ovulation).
In general, twins occur naturally at approximately the rate of 1/89 of singleton births, triplets at 1/89 the rate of twin births, and so on (Hellin's Law). However, for reasons that are unknown, the older a woman is, the more likely she is to naturally have a multiple birth.
The number of multiple births has increased over the last decades. For example, in Canada, between 1979 and 1999, the number of multiple birth babies increased 35%. Before the advent of ovulation-stimulating drugs, triplets were quite rare (approximately 1 in 8000 births) and higher order births so rare as to be almost unheard of. Much of the increase can probably attributed to the impact of fertility treatments, such as in vitro fertilisation. Younger patients who undergo treatment with fertility medication containing FSH followed by intrauterine insemination are at particular risk for multiple births of higher order.
Certain factors appear to increase the likelihood that a woman will naturally conceive multiples. These factors include:
- mother's age — women over 35 are more likely to have multiples than younger women
- mother's use of fertility drugs — approximately 35% of pregnancies arising through the use of fertility treatments such as IVF involve more than one child
The increasing use of fertility drugs as well as the increasing life expectancy for women have contributed to the rise in the rate of multiples over the last fifty years.
Recent increases over the last few years in the number of multiple births have also provoked concern over the risks to the fetus and also to the mother.
The greater the number of babies in a single pregnancy, the more likely they are to have a low birth weight, to be born prematurely and to consequently suffer medical problems. For example, in 1999, 53% of babies in multiple births were premature, compared to 7% of singletons. There is also a higher rate of stillbirths for multiples than for singletons.
Virtually all obstetrical risks are increased for the mother during a pregnancy with multiples. As many multiple pregnancies today are the result of the use of fertility therapy, efforts are being made to reduce the risks of multiple pregnancy, specifically triplets or more, by limiting the number of embryos per embryo transfer during IVF to one or two. Sometimes a selective reduction — the abortion of one or more of the multiple fetuses — is performed to give the pregnancy a higher chance of producing at least one healthy or live child.
Certain cultures consider multiple births a portent of either good or evil. A Korean tradition stating that triplets are 'lucky' has led to the seizure of all sets of triplets born in North Korea, apparently out of leader Kim Jong-il's fear that one may overthrow him in the future.
In Ancient Rome, the legend of the twin brothers who founded the city (Romulus and Remus) made the birth of identical twin boys a blessing, while identical twin girls were seen as an unlucky burden.
List of famous multiple births
- The Keys quadruplets (born on June 4,1915 in Hollis, Oklahoma), were the first same sex quadruplets known to survive to adulthood.
- The Dionne quintuplets (born on May 28, 1934 near Corbeil, Ontario, Canada) were the first quintuplets known to survive their infancy.
- The Creel Triplets - Leanna, Monica, and Joy born August 27, 1970 starred in Parent Trap 3, and Parent Trap 4: Hawaiian Honeymoon, two Disney made-for-TV movies.
- The Haden Triplets born in New York City on October 11, 1971 were Petra, Tanya and Rachel.
- The Rosenkowitz sextuplets (born on January 11, 1974 in Cape Town, South Africa) were the first sextuplets known to survive their infancy.
- The Walton sextuplets (born on November 11, 1983 in Liverpool) were the first sextuplets born in the United Kingdom known to survive their infancy.
- The Bergeson Triplets born in Baltimore, MD on October 17, 1984 were Ryan, Amy, and Jesse.
- The Frustaci septuplets (born on May 21, 1985) were the first septuplets to be born in the United States. Only three babies survived.
- The Williams Quadruplets born at Duke Hospital on February 14, 1987 were Elizabeth, Christopher, Michael, and James.
- The Dilley sextuplets (born on May 25, 1993 in Indianapolis) were the first surviving sextuplets to be born in the United States.
- The McCaughey septuplets (born on November 19, 1997 in Des Moines, Iowa) were the world's first surviving set of septuplets.
- The Humair septuplets (born on January 14, 1998 in Abha, Saudi Arabia) were the world's second surviving set of septuplets, born to a 40-year-old mother.
- The Brino quadruplets were born on September 21, 1998 in Woodland Hills, California to Tony and Shawna Brino, and have all appeared in the popular television series 7th Heaven when they were infants as the twin boys born in season 3- when they all started to look different the only girl (Miranda) stopped appearing in the show, and Zachary and Lorenzo starred in the first episode they were credited in. From then on, only Nikolas and Lorenzo Brino starred in the show, and did through the show's last season, season 10.
- The Chukwu octuplets (born in December 1998 in Houston) were the first set of octuplets born in the United States. The smallest of the octuplets, Odera, died a week after birth.
- The Qahtani septuplets (born on July 12, 2001 in Washington, DC) were the third set of septuplets to live past infancy.
- The Dahm Sisters were the only Playboy triplet centerfolds.
- The Armstrong triplets - Lil, Helen and Kate, were the first triplets to all be accepted to Cambridge University.
- The Saunders Triplets played the baby Harry Potter in the 2001 film "Harry Potter and the Sorcerer's Stone."
Fictional multiple births
- In the television series The Simpsons, Apu and Manjula Nahasapeemapetilon had octuplets: Anoop, Uma, Nabendu, Poonam, Pria, Sandeep, Sashi, and Gheet (also known as Lincoln, Freedom, Condoleezza, Coke, Pepsi, Manifest Destiny, Apple Pie, and Superman). They were a result of an overdosage of fertility drugs.
- The record was soon broken by a couple with nonuplets in Shelbyville, the archenemy of Springfield.
- In the television series Quintuplets, there are five children born simultaneously: Parker, Pierce, Patton, Penny, and Paige.
- In the movie Raising Arizona, the plot is largely driven by the protagonists' kidnapping of Nathan Arizona, Jr., one of a set of quintuplets.
- In the 1944 movie written and directed by Preston Sturges, The Miracle of Morgan's Creek, the "miracle" is the birth of sextuplets.
- A series story published on-line features the identical Carlson Septuplets.
- Among Disney characters, multiple births seem to be rather common. Donald Duck's nephews, Huey, Dewey and Louie are triplets; and so are Daisy Duck's nieces, April, May and June. Mickey Mouse's nephews, Morty and Ferdie Fieldmouse, are twins, as are Tweedledee and Tweedledum from Disney's Alice in Wonderland based on the Lewis Carroll stories. Even the Beagle Boys have a set of triplet descendants, the Beagle Brats. However, considering all of the characters mentioned are animals who commonly have multiple births (or hatchings) this is no great surprise.
- In Monty Python and the Holy Grail, Zoot and Dingo are identical twin sisters, both portrayed by Carol Cleveland.
- In Friends, Phoebe Buffay, herself an identical twin (her sister's name is Ursula), acted as a surrogate mother for the triplet babies of her brother and his wife, and she gave birth to two girls and a boy.
- The cartoon Powerpuff Girls consists of three girls, sisters, created at the same time. Triplets. Blossom, Bubbles and Buttercup.
- In the Metal Gear video game series, the player controls Solid Snake, one of a set of triplets who were cloned from Big Boss. The other two brothers, who play a crucial role in the storyline, are Liquid and Solidus.
- Tomax and Xamot, sometimes called the Crimson Twins or Crimson Guard Commanders, are the code names of identical twin brothers in the G.I. Joe universe and co-leaders of the [[Crimson Guard]
- In the Harry Potter book and movie series, there are two Gryffindor boys who are identical twins, Fred and George Weasley. Also in this series are Padma and Parvati Patil.
- The prolific mid 20th century British children's author, Elinor Brent-Dyer, had numerous cases of multiple births in her works. In the most extreme example, one extended family in her best known series, the Chalet School books, had nine sets of twins and one set of triplets over three generations.
- Articles on multiple births
- Mothers of Supertwins (MOST) - an international support group for families of triplets, quadruplets, quintuplets, or more offering support, information, resources, and much more.
- Ottawa Canada's Multiple Birth Families Association (MBFA)
- Facts About Multiples: an online encyclopedia of multiple births
- Multiple Births Foundation - aiding twins families and professionals caring for multiple birth families.
- - TAMBA - The web site of the only parent organisation in the UK providing information and support to couples who are expecting, or who have had, a multiple birth.
- National Organization of Mothers of Twins Clubs, Inc (NOMOTC) - A Support Group for Parents of Twins and Higher Order Multiples in the United States.
- MultipleBirth.com - A unique resource for research and information about the causes, effects and problems of multifetal pregnancy.
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