Mod Note: Some people may be squeamish about this subject, please keep all responses clinical rather than vulgar.
So, in my world, I try to play the "immortality" trope with twists that make it suitable for my imagination.
So, to understand the question, let me give you precise details:
- These immortals are 100% human, no vampires and such.
- This also implies that the source of immortality is physics-based, rather than chemistry or biology.
- The world we are talking about is an afterlife of some kind. Immortals here are immortals because they died in another world, and "arrive" to this world and live in their most recent healthy shape.
- People can die but they resurrect somewhere within the universe, nullifying every change on their bodies happened since their "initial" arrival.
TL;DR - these immortals are, let's say, people for who the "rules of time" do not apply appropriately, preventing them from aging.
Okay, this is a heavily disputable concept, please forgive me, I hadn't gone through every consideration yet. In fact, I ask this question to resolve one: fertility.
Needless to say that no afterlife can prevent becoming Hell, if its never-aging inhabitants can reproduce. Infinite life span implies several factors becoming infinite, too: this includes the potential amount of offspring. Well, not in the case of women, but let me bring it out later.
So, given this fact, I decided to make my immortals unable to make children. To avoid disturbing the human body's regular operation as much as possible, I decided to make it obvious at one single point: the merge of...those two cells, you know.
As a result, every fertilized ovum disintegrates immediately. I guess the amount of energy released from such a small mass can be practically unnoticeable, so it's fine.
This brings up a new consideration, though: the presence of ovum within immortal females' body is pointless. I'm really not sure if I should do something with it. The following outcomes are possible:
1) During 'arrival', all ovum disappears. This would cause a huge change in female hormone balance, if I know correctly.
2) Their amount is unchanged, but women have no periods. That would again, change the hormone balance, I'm almost sure of it, at least in the aspect that stopping periods is impossible without hormonal changes.
3) Ovum coming out disintegrates immediately, regardless of fertilization. This would prevent the need of hygienic precautions during "those" days, increasing comfort, but may possibly feel far-fetched for an audience. I want to make the rules to be as natural as possible.
4) No change applied in the matter. It is the most natural way of handling this question, but would imply that, in case of a biologically 20 years old woman, that decades later, when she's still 20 biologically, but 50 chronologically, she's out of these cells, inducing menopause. I repeat: menopause, in a biologically 20 years old woman. Not sure if I can (or even want to) handle this situation, as it implies hormonal changes.
Sorry for the long post, it was actually a portion of my worldbuilding process. It's hard to include "magic" while also trying to keep authenticity.
Is there a truly optimal method to handle this question?