What should be expected from the interaction between vampirism and pregnancy depends on what characteristics one chooses for the vampiric infection, and may also be affected by one's suppositions as to whether a fetus should be considered human and/or alive.
As an entity with a firm attachment to its hide in an intact condition, I hasten to add that these musings represent the purest speculation. No true wanderers of the night have any cause for outrage, regardless of their position in the choice/life/whatever street riot. The strains of vampirism tend to run along a continuum from biology to possession. The more mystical variants should be just as likely as other forms of magic to act on individual selves and lives, whose definition may become important.
Biological Models: Some types of vampirism, of which the infections described by P.N. Elrod or Lee Killough may be considered typical, operate very much like conventional diseases. Among humans, some pathogens cross the placenta and affect the fetus while others do not. The outcome of the vampiric conversion of a pregnant woman would probably depend on whether or not the entity responsible for the infection does so. If it does, the fetus should be sustained by the infection quite as well as the woman would be. The fetus might or might not ever be born, but there is no reason to expect a miscarriage. If pregnancy progresses, the infant should be a vampire also. If the infection does not cross the placenta, a female vampire, almost certainly non-breathing, would be unable to support a still-human fetus. It would die, and, one _hopes_, miscarry promptly.
Spirit models: Ricean vampires are infected with the spirit of a poltergeist that invaded the ancient queen Akasha. Many other wanderers of the night share a similar condition, in which the infection is not a living organism but a ghost or force transmitted according to more or less arbitrary rules. Here, one also ought to enquire whether the pregnant woman is (1) one life carrying another equivalent life, (2) a single entity, in which one life encompasses all, or (3) one life carrying a non-equivalent life or potential life in a relationship akin to parasitism.
Spirit model (two equivalent lives): The woman, not the fetus, is being infected. The infection could behave like either the placenta-crossing or non-crossing biological infections above.
Spirit model (one life): If the pregnant woman is a single life, a symbiotic entity, the vampiric spirit should maintain the unit in an unchanged condition... permanent pregnancy. Ouch.
Spirit model (two nonequivalent lives): This might result in miscarriage. If it did not, the outcome would imply that *all* of the living occupants of the human body participate in the vampiric transformation. The normal bacterial of the human intestine, any possible mundane pathogens, and any possible parasites, would all be transformed. Vampire tapeworms, anyone?
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Further thoughts:
Any of these models may permit (according to auctorial tastes) a woman to become infected in a way that does not kill her immediately. Very interesting (in the Chinese sense of the word) problems might arise if a living but infected woman became pregnant. Consider that a very large proportion of human pregnancies, probably more than half counting from fertilization, abort spontaneously due to implantation failures or defects in the fetus. What happens if the infection invades the fetus? Now a still-living woman is hosting something that, if it dies, will not stay dead. 64 cells, undead and hungry, might not become a problem. On the other hand, it might behoove a woman in this situation to seek sterilization with all possible haste.
With regard to dinoflagellates and taxonomy: The five-kingdom scheme isn't just a textbook convenience. It is intended to follow a proposal for the evolutionary origin of all eukaryotic organisms including the protista. (Crudely, anything fancier than a bacterium is a eukaryote.) The idea is that these organisms originated from parasitic or symbiotic associations between originally free-living bacteria-like ancestors. Mitochondria and chloroplasts do have some DNA of their own, so the arrangement is plausible. The kingdom Protista puts the single-celled eukaryotes together, because the details that give "plant", "animal" or "fungus" characteristics tend to emerge in multicellular organisms. Dinoflagellates are not the oddest example around. Wierder are beasties like _Euglena_, which normally has chloroplasts but can get by without them. Disagreements over this sort of thing amount to holy war, pursued by means of drive-by publication. (If you call viruses alive, it never stops. Viruses have all sorts of parasitic genome of their own. One would eventually have to call a single RNA or DNA base-pair a life-form, to the eternal amusement of chemists.)
Remember ... Biology is the study of plants and their parasites!
Source: Originally posted to the VAMPYRES list by Javelina
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As an entity with a firm attachment to its hide in an intact condition, I hasten to add that these musings represent the purest speculation. No true wanderers of the night have any cause for outrage, regardless of their position in the choice/life/whatever street riot. The strains of vampirism tend to run along a continuum from biology to possession. The more mystical variants should be just as likely as other forms of magic to act on individual selves and lives, whose definition may become important. 
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