Male pregnancy is the incubation of one or more embryos or fetuses by male members of some species. In nearly all heterogamous animal species, offspring are ordinarily carried by the female until birth, but in fish of the Syngnathidae family (pipefish, seahorses and the leafy seadragon), males perform this function. There are different ideas concerning whether a human male could become pregnant, and, by some definitions of gender identity, human men have become pregnant. Male humans incubating fetuses are also a recurring theme in speculative fiction.
Non-human animals
The Syngnathidae family of fish has the unique characteristic of a highly derived form of male brood care referred to as "male pregnancy". The family is highly diverse, containing around 300 different species of fish. Included in Syngnathidae are seahorses, the pipefish, and the weedy and leafy seadragons. The males of some of these species possess a brood pouch on the trunk or tail; in other species, the eggs are merely attached to the male's trunk or tail when the female lays them. Although biologists' definitions of pregnancy differ somewhat, all members of the family are considered by ichthyologists to display male pregnancy, even those without an external brood pouch.
Fertilization may take place in the pouch or in the water before implantation, but in either case, syngnathids' male pregnancy ensures them complete confidence of paternity. After implantation in or on the brood pouch or brood patch, the male incubates the eggs. Many species osmoregulate the brood pouch fluid to maintain proper pH for the developing embryos. In at least some species, the male also provisions his offspring with nutrients such as glucose and amino acids through the highly vascularized attachment sites in or on his body.
This period of incubation can take much longer than the production of another clutch of eggs by the female, especially in temperate regions where pregnancies last longer, leading to a reproductive environment in which sexual selection can be stronger on females than on males due to increased male parental investment. Interestingly, this reversal of traditional sex roles has only been found in pipefishes, whereas seahorses have largely been accepted as monogamous. Some pipefish species display classical polyandry because of this unique situation. Male syngnathids usually prefer females with large body size and prominent ornaments such as blue skin pigmentation or skin folds. Intriguingly, syngnathid males in some species are apparently capable of absorbing eggs or embryos while in the brood pouch. In these cases, embryos with the highest survival rate are those whose mothers display the preferred phenotype.
Syngnathidae is the only family in the animal kingdom to which the term "male pregnancy" has been applied.
Humans
Ectopic implantation
Human males do not have the anatomy needed for natural embryonic and fetal development. The theoretical issue of male ectopic pregnancy (pregnancy outside the uterine cavity) by implantation in biological males has been addressed by experts in the field of fertility medicine, who stress that the concept of ectopic implantation, while theoretically plausible, has never been attempted and would be difficult to justify â€" even for women lacking a uterus â€" owing to the extreme health risks to both the parent and child.
Robert Winston, a pioneer of in-vitro fertilization, told London's Sunday Times that "male pregnancy would certainly be possible" by having an embryo implanted in a man's abdomen â€" with the placenta attached to an internal organ such as the bowel â€" and later delivered by Caesarean section. Ectopic implantation of the embryo along the abdominal wall, and resulting placenta growth would, however, be very dangerous and potentially fatal for the host, and is therefore unlikely to be studied in humans. Gillian Lockwood, medical director of Midland Fertility Services, a British fertility clinic, noted that the abdomen is not designed to separate from the placenta during delivery, hence the danger of an ectopic pregnancy. "The question is not 'Can a man do it?'" stated bioethicist Glenn McGee. "It’s ’If a man does have a successful [ectopic] pregnancy, can he survive it?’"
Since 2000, several hoax web sites have appeared on the Internet purporting to describe the world's first pregnant man. While sometimes relying on legitimate scientific claims, in reality, no such experiment has ever been reported. Fertility clinician Cecil Jacobson claimed to have transplanted a fertilized egg from a female baboon to the omentum in the abdominal cavity of a male baboon in the mid-1960s, which then carried the fetus for four months; however, Jacobson did not publish his claims in a scientific journal, and was subsequently convicted on several unrelated counts of fraud for ethical misconduct.
Uterus transplantation
Unlike an ectopic pregnancy, which does not include the protection of a uterus, placing both the fetus and father in danger, having a uterus transplanted into a male would provide protection to both the fetus and the father and removing the danger to both.
According to Karine Chung, the director of the fertility preservation program at the University of Southern California's Keck School of Medicine, transplanting a uterus into a human male would not be much different from transplanting one into a female as, "Male and female anatomy is not that different." The uterus would either have to be donated by a willing donor or be tissue-engineered using the male's stem cells and then implanted into his pelvic region. Afterward, the standard in vitro fertilisation (IVF) procedure would be followed to insert the fetus into the male's newly formed womb.
A uterine transplant was performed in Saudi Arabia in 2000, from one woman to another, but it did not result in a pregnancy. This advance drew speculation about the possibility of a male receiving a womb transplant, and bearing a child from the transplanted womb.
Intersex people
Fertility has been documented in intersex people. An XY-predominant intersex person with true hermaphroditism (96% mosaic) can give birth. A case of an XY woman has been reported who experienced regular menstruation, two natural pregnancies, and gave birth.
Transgender males
Some transgender men can become pregnant. This is possible for transgender men who retain functioning ovaries and a uterus even after having otherwise physically transitioned to male.
Fetus in fetu
Fetus in fetu, though not an actual pregnancy, is an extremely rare condition in which a mass of tissue resembling a fetus forms inside the body. This is a developmental abnormality in which a fertilized egg splits as if to form identical twins, but one half becomes enveloped by the other, and an entire living organ system with torso and limbs can develop inside the host. The abnormality occurs in 1 in 500,000 live births in humans.
The case of Sanju Bhagat, also known as Sanjay Kumar, a man from Nagpur, India, attracted attention in 1999 for the length of time (36 years) he had carried his parasitic twin inside his body, and the size of the growth. Since Bhagat had no placenta, the growth had connected directly to his blood supply. In an extremely unusual case, a 2-year-old boy became pregnant with his parasitic twin inside his stomach feeding off him like a normal fetus would feed on its mother. The boy required a Caesarean section. It is virtually impossible that the fetus could survive this process due to being underdeveloped.
Popular culture
Thematically, pregnancy can be similar to the issues of parasitism and gender. Some science fiction writers have picked up on these issues, in "cross-gender" themesâ€"e.g., Octavia E. Butler's Bloodchild and Other Stories. Ursula K. Le Guin's novel The Left Hand of Darkness contains the sentence "The king was pregnant", and explores a society in which pregnancy can be experienced by anyone, since individuals are not sexually differentiated during most of their life and can become capable of inseminating or gestating at different times. Lois McMaster Bujold's Ethan of Athos features an all-male society in which men use artificial wombs, but experience many of the psychological effects of pregnancy (anticipation, anxiety, etc.). In Marge Piercy's feminist utopian novel Woman on the Edge of Time, neither men nor women get pregnant, leaving that to artificial wombs, but both sexes may lactate and nurse the infant; the specifically female experiences of pregnancy and nursing were opened to men in the cause of gender equality.
The concept of male pregnancy has been the subject of popular films, generally as a comedic device. The 1978 comedy film Rabbit Test stars Billy Crystal as a young man who inexplicably becomes pregnant instead of his female sex partner. The 1990 BBC television comedy drama Frankenstein's Baby features a Dr. Eva Frankenstein helping a male patient to become the world's first pregnant man. The 1994 science fiction comedy/drama Junior stars Arnold Schwarzenegger as a fertility researcher who experiments on himself; the screenplay was inspired by a 1985 article in Omni magazine.
The concept appears frequently as a comedic gag in movie and television programs. In Monty Python's 1979 film, Life of Brian, there is a political satire scene in which a character demands that any man has a "right to have babies if he wants them," which is ridiculed as impossible. In the BBC science fiction comedy series Red Dwarf, the main character, Lister, becomes pregnant after having sex with a female version of himself in an alternate universe. In an episode of Sliders, the quartet "slides" into an alternate world in which babies develop during their final months in the father because a worldwide disease has kept women from being able to carry children beyond their first trimester. In the popular fantasy series Charmed's fifth season, during a dream spell gone wrong, Leo ends up pregnant with Piper's baby for a good deal of the episode, leading to her referring to him as an 'incubator' and at times berating him for 'upsetting the baby'.
The possibility of extraterrestrial life having different reproductive sexuality is the basis for many references. In the Star Trek: Enterprise episode "Unexpected", Trip Tucker becomes pregnant with the offspring of a female of another species. In the video game The Sims 2 male characters can be impregnated via cheat codes or alien abduction. In the American Dad! episode "Deacon Stan, Jesus Man", the boy Steve becomes impregnated after giving the mouth-to-mouth resuscitation to the extraterrestrial Roger, then unwittingly passes it on to his girlfriend via a kiss. In the animated series Futurama, the extraterrestrial Kif can be impregnated by a touch. In the SciFi Channel miniseries, Farscape: The Peacekeeper Wars, the extraterrestrial Rygel becomes impregnated with human John and Aeryn's baby. In the series Alien Nation, when Tectonese main character George Francisco and his wife Susan decide to have a third child, it is revealed that, in order to conceive, a Tectonese couple needs a third party, called a binnaum, to complete impregnation, and that the male carries the babyâ€"encased in a podâ€"during the final months of gestation. In the Ren & Stimpy "Adult Party Cartoon" episode "Stimpy's Pregnant" features Stimpy who is pregnant but Mr. Horse finds out that he is actually constipated. In the animated series The Fairly OddParents in the TV film Fairly OddBaby, the fairy Cosmo was pregnant of Baby Poof. In the Ben 10: Alien Force episode "Save the Last Dance", it is revealed that Necrofriggians have an ability to asexually reproduce once every 80 years: building a large nest made of digested metal, where their eggs will hatch, then their offspring feed from metal and will first eat from the nest, before they instinctively will feed on solar plasma until they mature and starts their own separate lives. Due to the Necrofriggian reproduction cycle, Big Chill overtook Ben's personality to carry out the process, but Ben doesn't remember anything he does as Big Chill during this cycle, like he eats metal and had 14 babies, and felt very embarrassed when Gwen, Kevin and Julie explained, and Kevin's teasing and calling him "mommy" did not help. In the The Three Stooges episode "Even as IOU" Curly accidentally swallows a Vitamin Z pill meant for a horse. However, the error allows Curly to give birth to an Equidae, which the Stooges crown as a winning race horse.
Virgil Wong, a performance artist, created a hoax site featuring a fictitious male pregnancy, claiming to detail the pregnancy of his friend Lee Mingwei.
Male pregnancy is also commonly explored in slash (homosexual) fan fiction, usually based upon fantasy series such as Supernatural or Harry Potter.