When a character's pregnancy is complicated by supernatural means - be it Bizarre Alien Biology, Functional Magic, or even through a Mad Scientist. There are three ways this could work:
- Supernatural conception: The pregnancy is unnatural from the very beginning, such as Jesus's conception in The Bible. Half Human Hybrids and babies conceived through Mpreg are examples of this. This is normally a good time to exclaim "But I Can't Be Pregnant!," where there is understandable reason to be surprised about the pregnancy.
- Supernatural pregnancy: The baby is conceived normally, but during pregnancy something mystical happens to the mother and/or the fetus. Unfortunate women subjected to experimentation either through a Mad Scientist or a Back-Alley Doctor can end up with this.
- Both. The baby is conceived and carried to term through supernatural means.
- Horrific example from Berserk: Guts and Casca's child, conceived in their moment of love by the waterfall, was corrupted by the demonic seed of the newly-born Femto, who raped Casca during the events of the Eclipse.
- Further example from Berserk: Ganishka's demon-soldiers are created by dropping heavily-pregnant women into vats of demonically-charged amniotic fluid which instantly corrupts and mutates the foetus into a demon, who then claws and bites his way out of the womb.
- The Invisible Woman of the Fantastic Four had already had a difficult prenancy with her first child, Franklin. Susan's second child was conceived in the Negative Zone, and resulted in a stillbirth.
- The plot of the comic book series America's Got Powers begins when an alien crystal falls to Earth and gives off a burst of energy. All of the pregnant women within range, regardless of how far along they were, immediately give birth to fully-developed, healthy, super-powered babies.
- The Boys: Billy's wife dies when her superpowered fetus (she'd been raped by a super) explodes out of her uterus, floating in the air and firing Eye Beams. He kills it with a table lamp.
- Rosemary's Baby involved a young woman getting prescribed mysterious drugs by her doctor during her pregnancy, which she comes to suspect aren't legitimate treatments but something more sinister... but it is too late, and she births an Enfant Terrible (implied as possibly The Antichrist).
- The Phantom Menace hints that Anakin Skywalker (aka Darth Vadar) was conceived this way.
- Blade's mother was bitten by a vampire not long before he's born. The result: He's a Dhampyr.
- In Angel this happens to Cordelia a couple of times.
- In an early episode she has a one-night-stand with a guy who turns out to be a demon and has impregnated her, and the baby grows and almost comes to term in just a few days.
- Jasmine somehow impregnated Cordy with herself and uses Cordy's body as an incubator.
- Tim doesn't believe that Corinne's baby is his because she's showing after only a few weeks of pregnancy. She insists that it's Tim's baby, and ends up giving birth after only a month or so. It turns out that the baby is possessed by the devil.
- Mary is pregnant with Burt's child, but she's not sure it's his - she conceived at around the same time when he had been kidnapped by aliens & replaced by an alien doppelganger, so it might be half alien.
- In Twilight: Bella gets pregnant with Edward's half-vampire child that develops abnormally quickly, putting her life in danger
- In the Elder Races stories by Thea Harrison, the pregnancy resulting from the marriage of Dragos Cuelebre and Pia Giovanni was complicated to say the least. For starters, Dragos is actually an immortal dragon in human form and Pia is the offspring of a human and a unicorn in human form; Pia herself can turn into a unicorn.. Since the pregnancy was utterly unprecedented, no one knew for sure how long it would go on or what form the offspring would take. Fortunately at nine months, the fetus transformed itself in utero to a human baby and was born normally
- A Song of Ice and Fire: Daenerys's pregnancy starts off normal, but after she asks a witch to perform Blood Magic to save her husband, the witch complicates Daenerys's pregnancy, leading her to birth a horrific reptilian baby that may have damaged Daenerys's womb and rendered her incapable of bearing children forever. (Or did it?)
- From The Mortal Instruments: Jocelyn's husband experimented on her while she was pregnant both times, giving her daughter Clary angel's blood and her son Jonathan Christopher demon's blood, resulting in supernatural powers.
- Thief of Time: the Anthropomorphic Personification of Time goes through one of these, essentially having the same birth twice, with the end result being one soul going in two children. Nanny Ogg, who was the midwife, was quite surprised, as she told herself (literally).
- In Dune, Lady Jessica drinks and transforms the Water of Life for the Fremen seitch while pregnant with Alia. Due to that Alia is born with uncanny psychic powers and the memories (and as seen later, multiple personalities) of all her ancestors—a condition the Bene Geserit foresaw (or probably had seen from prior experience) as coming from such circumstances, to be avoided as "abomination".
- In The Ramayana, the god Vishnu turns himself into celestial porridge (no, seriously) that King Dasaratha is supposed to feed to his wives. All three of them subsequently give birth to sons that are endowed to different degrees with Vishnu's essence.
- From The Bible:
"How will this be," Mary asked the angel, "since I am a virgin?"The angel answered, "The Holy Spirit will come on you, and the power of the Most High will overshadow you. So the holy one to be born will be called the Son of God."- Luke 1:34-35
- Jesus' mother Mary was an unwed virgin. She became pregnant directly by the power of God, without the need for sex.
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