Male pregnancy is the carrying of one or more embryos or fetuses by the male of any species inside their bodies. The majority of all pregnancies in the animal kingdom are carried by female organisms. In most heterogamous species, the males produce the spermatazoa and rarely host the zygote.
The Syngnathidae family of fish includes seahorses, the pipefish, and the weedy and leafy sea dragons. This family of fish have the unique characteristic where females lay their eggs in a brood pouch on the male's chest, and the male then fertilizes and incubates the eggs. It is the only family in the animal kingdom to which the term "male pregnancy" has been applied.
Speculation on inducing pregnancy in men
British physician Robert Winston speculates that it may be possible to surgically induce abdominal ectopic pregnancy in men. In his book The IVF Revolution, Winston speculates that an embryo could be implanted in a man's abdomen—with the placenta attached to an internal organ such as the bowel—and that the baby would later be delivered by Caesarean section. However, other experts expressed great concerns about the safety of such a procedure.
Pregnancy among transsexual and intersex people
Some female-to-male transsexuals who interrupt hormone treatments can become pregnant, while still identifying and living as male—this is possible for individuals who still have functioning ovaries. One example is Matt Rice, a transman who is the former partner of writer Patrick Califia. Rice bore a child by artificial insemination. Although the individual is genetically and physiologically female, from an identity standpoint this may be considered by some a "male pregnancy".
Human male pregnancy in fiction
Thematically, pregnancy can be related to issues of parasitism and gender. Some science fiction writers have picked up on these issues, in "cross-gender" themes—e.g., Octavia Butler's Bloodchild. 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, but men may take drugs to lactate and nurse the infant; the experience of "pregnancy" and the woman-only experience of nursing were sacrificed for gender equality. In the Internet comedy series Red vs. Blue, the character of Template:Rvbchar is impregnated by a parasitic embryo from an alien creature. Roger Corman's B-film Night of the Blood Beast  (1958) featured a male scientist being impregnated by an alien. Sheri Tepper uses male pregnancy as a form of political commentary in The Fresco when intergalactic peace officers take politicians at their literal word that all life is sacred despite any personal drawbacks.
Male pregnancy is frequently seen in fan fiction (such as famous actors) such stories may be denoted as "mpreg", a term coined by two writers under the pseudonyms of Taleya Joinson and Texas Ranger, who created and maintained what is believed to be the first fan fiction archive dedicated to stories of this genre in 1998. The pregnancies may be the result of advanced medical technology (e.g., experiments on Mulder from The X-Files), mystical pregnancies, magic or are unexplained.
Various mythologies have featured male characters birthing, but such events typically either take place in an entirely different fashion than an ordinary female pregnancy, such as Athena springing fully-formed from Zeus's forehead, or Dionysius being born from his thigh. Male mythological figures may also become pregnant when rendered female in some way, such as the shapeshifter Loki turning into a mare to distract a stallion and ending up giving birth to Sleipnir.
Human male pregnancy in popular culture
Two comedy films centered around the theme of such an event in humans, Rabbit Test (1978) and Junior (1994), have been released. The latter's attempts are somewhat scientifically feasible; the former does not address the matter. Television episodes and series have featured such pregnancies as a result of alien-human interaction, including Futurama, American Dad!, Alien Nation, Dilbert and the episode "Unexpected" of Star Trek: Enterprise, as well as in the computer game The Sims 2, "which in Strangetown men can be gay and have babies".There are also rumors and hoaxes on the subject for actual achievements.
- If a "Sim" (a human simulation from the computer game The Sims 2) stargazes with a telescope, he/she may be abducted by aliens. If it is an adult male, he will get pregnant with an alien baby. Likewise, the Sim will eventually give birth like female Sims do.
- In an episode of Charmed, Leo becomes pregnant with Piper's baby for a short term.
- In Full House Jesse carries around a "sympathy path" to simulate being pregnant as a bet with his wife and an elderly man claims to have seen a pregnant man.
- In the first episode of Torchwood Captain Jack mentions that he once got pregnant.
- In an episode of Red Dwarf, Lister becomes pregnant after visiting a parallel universe where male and female are reversed and he has sex with his counterpart.
- An episode of Sliders depicts a universe where men carry children to term because women lost the ability in a catastrophic disaster.
- In an episode of Futurama, Kif becomes pregnant with Leela's DNA, but claims Amy as his "Smizmar" and therefore the mother.
- The Cosby Show's seventh season features a dream sequence episode where a volcanic eruption releases spores causing male pregnancy and several characters fall victim; they ultimately give birth to nonhuman objects such as a model sailboat and a submarine sandwich.
- In the movie Billy Madison, Billy makes a wisecrack about Eric getting pregnant (referring him to being a potential soccer player).
- In the sitcom Step by Step, Frank and J.T. make a bet with Carol and Dana that they can handle being pregnant better than women by stuffing really heavy objects in their shirts and walking around like that for a few days. They ultimately give up and lose.
- Sam Beckett occupies the body of a pregnant woman during an episode of Quantum Leap and at the show's conclusion gives birth to the child. The Quantum Leap premise is such that along with Sam, and possibly his friend Al, the viewer is the only one capable of seeing actor Scott Bakula's physical form in place of the currently possessed body, prompting speculation as to what it must have looked like during the child's delivery. Nevertheless, the director of photography refrained from including footage of Sam's genital area.
- A hoax site, "www.malepregnancy.com" monitoring a fictitious male pregnancy. Mr. Lee has been "expecting" since December of 1999.
- In an episode of Round The Twist, Pete Twist becomes pregnant after urinating on a tree inhabited by a female tree spirit. The subsequent child is also a tree spirit, eventually birthed through Pete's navel, and takes up residence in a once-sickly tree next to its mother's.
- In Beavis & Butthead, they watch a film in which the female character gives birth. This leads to Beavis believing he is pregnant too but it turns out that he was merely having muscle spasms.
- Jones, Adam G. (2003-10-14). "Male Pregnancy" (HTML). Current Biology. 13 (20): R791. Unknown parameter
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- "Babies borne by men `possible'". The Independent. February 22, 1999.
- Khadilkar, Vaman. "Intersex Disorders", Pediatrician On Call web site
- Faster than Life
- Two Dads With a Difference—Neither of Us Was Born Male, Village Voice, June 21, 2000.
- Piercy, Marge (1985-11-12). Woman on the Edge of Time. Fawcett. ISBN 0-449-21082-0. Check date values in:
-  Wayback archival reference
- "A hoax site featuring a fictitious male pregnancy".
- A Womb of His Own, Snopes debunks the hoax.