I have wrote stories of similar premise. I really like this concept and would like to see a full story about it
I, too, have always had a fantasy about getting used by some xenomorph creature or an alien with an ovipostor of some kind. Either having an egg or a creature be birthed by me in a slow build up way. Edging almost for 10 or more hours. Prefer a large egg though when it comes to the climax, so when I orgasm it's pushed out by a strong contraction. The alien then finding me and repeating the task again only to give me two eggs next. Would have it as a rapid pregnancy too so that the full feeling was turning me on just as rapidly. The alien creature then searching my sex eager for the eggs to come out. I have so many of these fantasies though.
I've been role playing for years through different scenarios but the main one i do is that i play a humanoid alien with tentacles for cocks looking for breeders on earth to lure back to my cabin in the woods which is also an underground research base.We reproduce via eggs that can be implanted orally,anally,vaginally and even into breasts,they start off small like beads but in a few weeks grow to the size of baseballs but each pregnancy is about 3-5 thousand eggs.
I just recently came up with a roleplay idea that has more to do with a dominant partner and myself being submissive when it comes to foced and rapid impegnation and births. Goes something like this: A man practically has me captive for his pleasures and his biggest tick is getting women pregnant and forcing them to give birth. It starts our with pregnancy roleplay, he makes me wear a fake belly for a while then I have to pretend to give birth every night. Well then it gets a little deeper, he moves on to actually focibly impregnating me and making me give birth, where he determines he REALLY enjoys it and becomes more obsessed with the idea of watching me like this. He then has an idea to concoct a syrum he can inject me with and rapidly impregnate over the course of 3 hrs. So for 3 hours he watches my belly grow huge, etc. After the 3 hours he forces me into labor and giving birth. This takes place every night so that I can fulfill his obsessive fantasies in a woman being pregnant and giving birth in numerous different scenerieos. To include giving birth on my own, giving birth with him helping me, giving birth with just us, giving birth in public, giving birth in the woods, giving birth in an isolated cabin, giving birth in a vehicle, giving birth to an alien and even torturing me as I'm giving birth by preventing me from pushing, tieing me up or strapping me down on a table or chair, inserting objects including hands and fingers into me while I'm pushing, forcing me to stand up to birth, etc.