get a life
Omegas and alphas are an inspiration of the wrong perception of how sex works in animals. Most female animals don't have periods, so I guess it is the same for alphas and omegas. They are still fertile and go into heat. They just have different bodies. And every author builds their own universe, sometimes all gender can get pregnant, sometimes only females and omegas.
If you follow the estrous cycle from other mammals, the women probably won't have periods any longer.
Thanks for the rec. Here's a rec in return:
https://archiveofourown.org/series/7979
It's not Omegaverse (since it was written prior to the A/B/O trope), but it certainly has the elements for it. Though it's more like a combo of Children of Men + Handmaiden's Tale where a few males can carry babies (aptly called carriers). Kinda thought since your questions were regarding world-building, you'd like a fully-realised one.
1. Do women in omegaverse still have periods?
Based on most omegaverse manga that I've read, the A/B/O gender happened bcs there was a population decline crisis. So, evolutionary speking, wouldn't it be counterproductive if women in omegaverse still have periods? Especially in omega women since it meant they would have an infertility phase
2. If women in omegaverse do still have periods, and assuming women would be infertile during that time, does it only mean they couldn't get pregnant? Or they also couldn't impregnate other genders?
3. If all genders could get pregnant/impregnate, do omega women have separate organs to produce their "sperm"?
Most manga just mention about the existence of wombs in men (omega or all genders) but no one ever mention the existence of testicles in women (*if you've ever encountered one which mentioned about this, please kindly put the link below)
4. If women in omegaverse have periods, would the men have them too?
You know the biology of period, so why couldn't the men? Those men have wombs too
5. Bonus: does anyone here read "Claimed" by A.M. Arthur or "Alpha Heat" by Leta Blake? If you haven't, please read them, they're great