Superfetation
Superfetation (also spelt
superfoetation, based on a false
etymology — see
fetus) is the formation of a fetus while another fetus is already present in the
uterus. When there are two separate instances of
fertilisation during the same
cycle, rather than different cycles, it is known as
superfecundation.
It is claimed to be common in some species of animals, but is extremely rare in humans. It can occur only where there are two uteri, or where the
menstrual cycle continues through
pregnancy. Animals which have been claimed to be subject to superfetation include
rodents (
mice &
rats), farm animals (
horses &
sheep),
marsupials and
primates (
monkeys and
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. Superfetation has also been clearly demonstrated in
poeciliidae fish. [
1]
Flavia d'Angelo, an
Italian woman claiming to have become pregnant with triplets three months after initially getting pregnant, caused global media interest in 2001. [
2] However, it was later revealed to be a hoax. [
3]
*
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.
