Cuddles - Mutated foetus or was Shaw still infertile

Well plenty of Women who cant not have kids do still produce Eggs and still have their periods etc... Just like the male term shoot blanks does not mean nothing comes out.... So yes i would say that the Black Goo infected Sperm or DNA made Shaw be able to become fertile.... As i dont buy the Mutated Sperm theory, nope Sperm is nothing a Embryo is born from a Egg and that also explains why it had a umbilical cord attached.

I had an idea about this, actually. It's not likely that this was caused by a mutation; the Life-Cycle of the Trilobite-Alien was far too complex and was clearly by design because of it's resemblance to the original Xenomorph life-cycle. If you know enough about the Xenomorph you'll know that it is really more like a virus than an embryo- The facehugger uses enzymes to insert the aliens genetic material into a cell, which then grows like a tumor. My idea for this new breed of alien is that the engineers intended for the Trilobite's Genome to be sexually transmitted. If you are intrigued by any of my ideas, write me back and i'll give you more of the details i worked out in my head. This is, of course, just an idea. I'm sure whatever the writers decide is the official story will shock us all.

Well, the parasite/goo is an alien life form (created or otherwise), and as we know or can guess aliens do strange things. Entirely plausable that the parasite/goo infecting Holloway was able to modify his sperm just as it was modifying his DNA (as we saw it does in the beginning of the movie) and allow it to bring life to this one egg. But as David said, it's "not your normal fetus". Not to mention the fast growth...I don't think it was entirely option two, but a bit of both.

As BigDave said, the fact that Shaw was infertile doesnt means that she cant produce ovum. I guess the black goo has mutated Charlie sperm and thus it fecundates Shaw egg and made the foetus capable to evolve. I don't belive the black goo can be transmited from one infected person to an healthly one. If that happens, Shaw must be mutated at the end of the movie, as well as Ripley in Alien 3 as any disease acquired for a pregnant woman can pass to the foetus and vice-versa.. Whe never saw an alien infecting an human being with black goo.