Superfetation
Encyclopedia
Superfetation is the simultaneous occurrence of more than one stage of developing embryo in the same animal. In mammals it manifests as the formation of a fetus from a different menstrual cycle while another embryo is already present in the uterus
. When there are two separate instances of fertilisation
during the same cycle
, it is known as superfecundation
.
Superfetation is claimed to be common in some species of animals, but is extremely rare in humans. In mammals it can occur only where there are two uteri, or where the menstrual cycle
continues through pregnancy
. The risk with superfetation is that the second baby is often born prematurely, which can increase its odds of experiencing lung development problems.
s (mice
and rat
s), farm animals (horse
s and sheep), marsupials (kangaroo
s and sugar glider
s), and primate
s (humans). Superfetation has also been clearly demonstrated in poeciliid fish
In 1960, John and Mary Tress of Baltimore MD had what the nurse called twins, she was wrong. Dr Paul C Weinberg of Mt.Sinai hospital delivered the boys Anthony John and Mark Francis and realized that Anthony born five minutes before his brother Mark looked premature. Immediately Dr Weinberg did x-rays of the boys thigh bones and noticed a disparity in bone age. Mark a full term baby born five minutes after his 2 months premature brother Anthony. Anthony was conceived a full 2 months after his brother Mark, {Newsweek Magazine, July 31. 1961}
In 1992, Taylor and Evan Barth, conceived 4 weeks apart, were born in Hawaii, USA to Michelle and John Barth. Taylor, the one conceived later was born first.
In 2007 Ame and Lia Herrity, conceived 3 weeks apart, were born in the United Kingdom to Amelia Spence and George Herrity.
In May 2007 Harriet and Thomas Mullineux, also conceived 3 weeks apart, were born in Benfleet, Essex, UK to Charlotte and Matt Mullineux.
In 2009, Todd and Julia Grovenburg of Fort Smith, Arkansas received international media attention for Mrs. Grovenburg's conception of an additional child while already pregnant with a child conceived two and a half weeks earlier. If it were possible to carry both children to term, the birth of the first child would be expected in December 2009, whereas the second child would be due in January 2010. Grovenburg's obstetrician reported that cases of superfetation "can only be confirmed after delivery by chromosomal and metabolic studies on the baby." Both healthy babies were delivered through Caesarean section
on 2 December 2010.
Uterus
The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...
. When there are two separate instances of fertilisation
Fertilisation
Fertilisation is the fusion of gametes to produce a new organism. In animals, the process involves the fusion of an ovum with a sperm, which eventually leads to the development of an embryo...
during the same cycle
Menstrual cycle
The menstrual cycle is the scientific term for the physiological changes that can occur in fertile women for the purpose of sexual reproduction. This article focuses on the human menstrual cycle....
, it is known as superfecundation
Superfecundation
Superfecundation is the fertilization of two or more ova from the same cycle by sperm from separate acts of sexual intercourse. The term superfecundation is derived from fecund, meaning the ability to produce offspring....
.
Superfetation is claimed to be common in some species of animals, but is extremely rare in humans. In mammals it can occur only where there are two uteri, or where the menstrual cycle
Menstrual cycle
The menstrual cycle is the scientific term for the physiological changes that can occur in fertile women for the purpose of sexual reproduction. This article focuses on the human menstrual cycle....
continues through pregnancy
Pregnancy
Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...
. The risk with superfetation is that the second baby is often born prematurely, which can increase its odds of experiencing lung development problems.
In animals
Animals that have been claimed to be subject to superfetation include rodentRodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
s (mice
Mouse
A mouse is a small mammal belonging to the order of rodents. The best known mouse species is the common house mouse . It is also a popular pet. In some places, certain kinds of field mice are also common. This rodent is eaten by large birds such as hawks and eagles...
and rat
Rat
Rats are various medium-sized, long-tailed rodents of the superfamily Muroidea. "True rats" are members of the genus Rattus, the most important of which to humans are the black rat, Rattus rattus, and the brown rat, Rattus norvegicus...
s), farm animals (horse
Horse
The horse is one of two extant subspecies of Equus ferus, or the wild horse. It is a single-hooved mammal belonging to the taxonomic family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today...
s and sheep), marsupials (kangaroo
Kangaroo
A kangaroo is a marsupial from the family Macropodidae . In common use the term is used to describe the largest species from this family, especially those of the genus Macropus, Red Kangaroo, Antilopine Kangaroo, Eastern Grey Kangaroo and Western Grey Kangaroo. Kangaroos are endemic to the country...
s and sugar glider
Sugar Glider
The sugar glider is a small gliding possum originating from the marsupial family.The sugar glider is native to eastern and northern mainland Australia and is also native to New Guinea and the Bismarck Archipelago.- Habitat :Sugar gliders can be found all throughout the northern and eastern parts of...
s), and primate
Primate
A primate is a mammal of the order Primates , which contains prosimians and simians. Primates arose from ancestors that lived in the trees of tropical forests; many primate characteristics represent adaptations to life in this challenging three-dimensional environment...
s (humans). Superfetation has also been clearly demonstrated in poeciliid fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
In humans
Reports of superfetation occurring long after the first impregnation have often been treated with suspicion, and some have been clearly discredited. Other explanations have been given (and demonstrated) for different levels of development between twins. Artificially induced superfetation has, however, been demonstrated, although only up to a short period after insemination.In 1960, John and Mary Tress of Baltimore MD had what the nurse called twins, she was wrong. Dr Paul C Weinberg of Mt.Sinai hospital delivered the boys Anthony John and Mark Francis and realized that Anthony born five minutes before his brother Mark looked premature. Immediately Dr Weinberg did x-rays of the boys thigh bones and noticed a disparity in bone age. Mark a full term baby born five minutes after his 2 months premature brother Anthony. Anthony was conceived a full 2 months after his brother Mark, {Newsweek Magazine, July 31. 1961}
In 1992, Taylor and Evan Barth, conceived 4 weeks apart, were born in Hawaii, USA to Michelle and John Barth. Taylor, the one conceived later was born first.
In 2007 Ame and Lia Herrity, conceived 3 weeks apart, were born in the United Kingdom to Amelia Spence and George Herrity.
In May 2007 Harriet and Thomas Mullineux, also conceived 3 weeks apart, were born in Benfleet, Essex, UK to Charlotte and Matt Mullineux.
In 2009, Todd and Julia Grovenburg of Fort Smith, Arkansas received international media attention for Mrs. Grovenburg's conception of an additional child while already pregnant with a child conceived two and a half weeks earlier. If it were possible to carry both children to term, the birth of the first child would be expected in December 2009, whereas the second child would be due in January 2010. Grovenburg's obstetrician reported that cases of superfetation "can only be confirmed after delivery by chromosomal and metabolic studies on the baby." Both healthy babies were delivered through Caesarean section
Caesarean section
A Caesarean section, is a surgical procedure in which one or more incisions are made through a mother's abdomen and uterus to deliver one or more babies, or, rarely, to remove a dead fetus...
on 2 December 2010.
External links
- Superfetation in Beef Cattle Cattle Doctoral Thesis; Joel Andrew Carter, Louisiana State University, Defended 2002-03-18
- Superfetation in fish
- A case of twins with probable superfetation a report of a case of superfetation demonstrated through different paternity of twins.