
I think it's via C-section, a few Omegaverse Mpregs ive read have shown the scars the birthing dad had.
I still don't how the whole uterus via the butthole works either Looool! And when i read non-omegaverse BLs and the seme say some shit like "your so wet down here" i like... sir =_= that's anal leakage bruh (〜 ̄△ ̄)〜... you need a doctor

We can assume that the liquid omegas excrete also keep the area (somewhat) sanitized, the way a vagina keeps itself (mostly) clean. We can also assume that the doctors would clean the area prior to childbirth. I think most just go for C-Section though.
Also a lot of omegaverse stories imply that omegas didn’t always exist and genetic mutations occurred.
Now that I think about it. How are the babies even born? Like women can have children because we have vaginas but men don't and these types of stories don't have people with both parts so have are the men going to give birth? Yeah they can give birth throw their ass but wouldn't that cause the baby to have all types of infections or problems because of the poop? Also I doubt they would give birth through their penis because it would literally rid in HALF BUT they can do a C-section that would make more sense but what about the ancestors? They didn't have C-sections if they did they would have a very painful and short life because of infections.