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Superfecundation is the fertilization of two or more ova from the same cycle by sperm from separate acts of sexual intercourse, which can lead to twin babies from two separate biological fathers. [1] [2] The term superfecundation is derived from fecund, meaning able to produce offspring. Homopaternal superfecundation is fertilization of two separate ova from the same father, leading to fraternal twins, [3] while heteropaternal superfecundation is a form of atypical twinning where, genetically, the twins are half siblings – sharing the same mother, but with different fathers.
Sperm cells can live inside a female's body for up to five days, and once ovulation occurs, the egg remains viable for 12–48 hours before it begins to disintegrate. [4] Superfecundation most commonly happens within hours or days of the first instance of fertilization with ova released during the same cycle.
Ovulation is normally suspended during pregnancy to prevent further ova becoming fertilized and to help increase the chances of a full-term pregnancy. However, if an ovum is atypically released after the female was already impregnated when previously ovulating, a chance of a second pregnancy occurs, albeit at a different stage of development. This is known as superfetation. [5]
Heteropaternal superfecundation is common in animals such as cats and dogs. Stray dogs can produce litters in which every puppy has a different sire. Though rare in humans, cases have been documented. In one study on humans, the frequency was 2.4% among dizygotic twins whose parents had been involved in paternity suits. [6]
In 1982, twins who were born with two different skin colors were discovered to be conceived as a result of heteropaternal superfecundation. [7] [5]
In 1995, a young woman gave birth to diamniotic monochorionic twins, who were originally assumed to be monozygotic twins until a paternity suit led to a DNA test. This led to the discovery that the twins had different fathers. [3]
In 2001, a case of spontaneous monopaternal superfecundation was reported after a woman undergoing IVF treatments gave birth to quintuplets after only two embryos were implanted. Genetic testing supported that the twinning was not a result of the embryos splitting, and that all five boys shared the same father. [5] [8]
In 2008, on the Maury Show a paternity test on live television established a heteropaternal superfecundation. [9]
In 2015, a judge in New Jersey ruled that a man should only pay child support for one of two twins, as he was only the biological father to one of the children. [10]
In 2017, an IVF-implanted surrogate mother gave birth to two children: one genetically unrelated child from an implanted embryo, and a biological child from her own egg and her husband's sperm. [11]
In 2019, a Chinese woman was reported to have two babies from different fathers, one of whom was her husband and the other was a man having a secret affair with her during the same time. [12]
In 2022, a 19-year-old Brazilian from Mineiros gave birth to twins from two different fathers with whom she had sex on the same day. [13]
Greek mythology holds many cases of superfecundation:
Fertilisation or fertilization, also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give rise to a zygote and initiate its development into a new individual organism or offspring. While processes such as insemination or pollination, which happen before the fusion of gametes, are also sometimes informally referred to as fertilisation, these are technically separate processes. The cycle of fertilisation and development of new individuals is called sexual reproduction. During double fertilisation in angiosperms, the haploid male gamete combines with two haploid polar nuclei to form a triploid primary endosperm nucleus by the process of vegetative fertilisation.
In vitro fertilisation (IVF) is a process of fertilisation in which an egg is combined with sperm in vitro. The process involves monitoring and stimulating a woman's ovulatory process, then removing an ovum or ova from her ovaries and enabling a man's sperm to fertilise them in a culture medium in a laboratory. After a fertilised egg (zygote) undergoes embryo culture for 2–6 days, it is transferred by catheter into the uterus, with the intention of establishing a successful pregnancy.
Amphitryon, in Greek mythology, was a son of Alcaeus, king of Tiryns in Argolis. His mother was named either Astydameia, the daughter of Pelops and Hippodamia, or Laonome, daughter of Guneus, or else Hipponome, daughter of Menoeceus. Amphitryon was the brother of Anaxo, and Perimede, wife of Licymnius. He was a husband of Alcmene, Electryon's daughter, and stepfather of the Greek hero Heracles.
Twins are two offspring produced by the same pregnancy. Twins can be either monozygotic ('identical'), meaning that they develop from one zygote, which splits and forms two embryos, or dizygotic, meaning that each twin develops from a separate egg and each egg is fertilized by its own sperm cell. Since identical twins develop from one zygote, they will share the same sex, while fraternal twins may or may not. In very rare cases fraternal twins can have the same mother and different fathers.
A multiple birth is the culmination of one multiple pregnancy, wherein the mother gives birth to two or more babies. A term most applicable to vertebrate species, multiple births occur in most kinds of mammals, with varying frequencies. Such births are often named according to the number of offspring, as in twins and triplets. In non-humans, the whole group may also be referred to as a litter, and multiple births may be more common than single births. Multiple births in humans are the exception and can be exceptionally rare in the largest mammals.
Artificial insemination is the deliberate introduction of sperm into a female's cervix or uterine cavity for the purpose of achieving a pregnancy through in vivo fertilization by means other than sexual intercourse. It is a fertility treatment for humans, and is a common practice in animal breeding, including dairy cattle and pigs.
The human female reproductive system is made up of the internal and external sex organs that function in the reproduction of new offspring. The reproductive system is immature at birth and develops at puberty to be able to release matured ova from the ovaries, facilitate their fertilization, and create a protective environment for the developing fetus during pregnancy. The female reproductive tract is made of several connected internal sex organs—the vagina, uterus, and fallopian tubes—and is prone to infections. The vagina allows for sexual intercourse, and is connected to the uterus at the cervix. The uterus accommodates the embryo by developing the uterine lining.
Assisted reproductive technology (ART) includes medical procedures used primarily to address infertility. This subject involves procedures such as in vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI), cryopreservation of gametes or embryos, and/or the use of fertility medication. When used to address infertility, ART may also be referred to as fertility treatment. ART mainly belongs to the field of reproductive endocrinology and infertility. Some forms of ART may be used with regard to fertile couples for genetic purpose. ART may also be used in surrogacy arrangements, although not all surrogacy arrangements involve ART. The existence of sterility will not always require ART to be the first option to consider, as there are occasions when its cause is a mild disorder that can be solved with more conventional treatments or with behaviors based on promoting health and reproductive habits.
Embryo transfer refers to a step in the process of assisted reproduction in which embryos are placed into the uterus of a female with the intent to establish a pregnancy. This technique - which is often used in connection with in vitro fertilization (IVF) - may be used in humans or in other animals, in which situations and goals may vary.
Third-party reproduction or donor-assisted reproduction is any human reproduction in which DNA or gestation is provided by a third party or donor other than the one or two parents who will raise the resulting child. This goes beyond the traditional father–mother model, and the third party's involvement is limited to the reproductive process and does not extend into the raising of the child. Third-party reproduction is used by couples unable to reproduce by traditional means, by same-sex couples, and by men and women without a partner. Where donor gametes are provided by a donor, the donor will be a biological parent of the resulting child, but in third party reproduction, he or she will not be the caring parent.
Male pregnancy is the incubation of one or more embryos or fetuses by organisms of the male sex in some species. Most species that reproduce by sexual reproduction are heterogamous—females producing larger gametes (ova) and males producing smaller gametes (sperm). In nearly all animal species, offspring are carried by the female until birth, but in fish of the family Syngnathidae, males perform that function.
Human fertilization is the union of an egg and sperm, occurring primarily in the ampulla of the fallopian tube. The result of this union leads to the production of a fertilized egg called a zygote, initiating embryonic development. Scientists discovered the dynamics of human fertilization in the 19th century.
Human sexual reproduction, to produce offspring, begins with fertilization. Successful reproduction typically involves sexual intercourse between a healthy, sexually mature and fertile male and female. During sexual intercourse, sperm cells are ejaculated into the vagina through the penis, resulting in fertilization of an ovum to form a zygote.
Controversy over the beginning of pregnancy occurs in different contexts, particularly as it is discussed within the debate of abortion in the United States. Because an abortion is defined as ending an established pregnancy, rather than as destroying a fertilized egg, depending on when pregnancy is considered to begin, some methods of birth control as well as some methods of infertility treatment might be classified as causing abortions.
In genetics, a non-paternity event occurs when an individual's presumed father is not in fact their biological father. This is a type of misattributed parentage experience (MPE) which can involve inaccurate assumptions made by an individual, their parents, or medical professionals. An NPE may result from sperm donation, closed adoption, heteropaternal superfecundation, promiscuity, paternity fraud, sexual assault, or medical errors during the process of assisted reproduction such as mixups during procedures such as in vitro fertilization and artificial insemination. Where there is uncertainty, the most reliable technique for establishing paternity is through genetic testing. Currently, there are many direct-to-consumer companies that offer paternity testing. Internationally, June 27 is recognized as NPE Awareness Day.
Pregnancy rate is the success rate for getting pregnant. It is the percentage of all attempts that leads to pregnancy, with attempts generally referring to menstrual cycles where insemination or any artificial equivalent is used, which may be simple artificial insemination (AI) or AI with additional in vitro fertilization (IVF).
Religious response to assisted reproductive technology deals with the new challenges for traditional social and religious communities raised by modern assisted reproductive technology. Because many religious communities have strong opinions and religious legislation regarding marriage, sex and reproduction, modern fertility technology has forced religions to respond.
Partner-assisted reproduction, reception of oocytes from partner (ROPA), reciprocal IVF,shared motherhood, partner IVF or co-IVF is a method of family building that is used by couples who both possess female reproductive organs. The method uses in vitro fertilization (IVF), a method that means eggs are removed from the ovaries, fertilized in a laboratory, and then one or more of the resulting embryos are placed in the uterus to hopefully create a pregnancy. Reciprocal IVF differs from standard IVF in that two partners are involved: the eggs are taken from one partner, and the other partner carries the pregnancy. In this way, the process is mechanically identical to IVF with egg donation. Reciprocal IVF offers the highest chance for pregnancy and a lower chance of a multiple births.
The history of in vitro fertilisation (IVF) goes back more than half a century. In 1959 the first birth in a nonhuman mammal resulting from IVF occurred, and in 1978 the world's first baby conceived by IVF was born. As medicine advanced, IVF was transformed from natural research to a stimulated clinical treatment. There have been many refinements in the IVF process, and today millions of births have occurred with the help of IVF all over the world.
Lesbian, gay, bisexual, and transgender people people wishing to have children may use assisted reproductive technology. In recent decades, developmental biologists have been researching and developing techniques to facilitate same-sex reproduction.
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