Please read the translators note on this page: http://www.mangago.me/read-manga/shounen_no_kyoukai/mf/c001/15/ Seems you missed it.
I dunno if you ignored my response, but the translators of this manga say that omegaverse in the image you gave is different. https://img.myreadingmanga.info/2016/10/b%EF%BC%8Dboy-Omegaverse_p001.jpg This comes from the bboy omegaverse. I used Google translate and it does say beta couples can have children, so I'm not sure why the translators said only omega can. Maybe because in the diagram, only omega have a womb pointed out.
i mean, obviously females can get pregnant. a, b, and o females. because... they're females... when i wrote "only omegas can get pregnant" i meant concerning MALES because... lol, this is a bl manga. the fuk i'm thinking about females for? LOL
and remember, the rules of abo are different based on the group. in TOP, everyone can get pregnant. in bboy and gateau (and i'm assuming ameiro... and hell, everyone else??), only omegas can get pregnant (well FEMALES and omega males).
I think it omega men and all women can pregnant. .. and omega men and women are a lot more fertile than beta and alfa women...alfa women are the hardest impregnate. I think they discriminate bcz they think of omega as weak specially since they go in heat and from what I gather they are apparently not as smart (which I don't get) and alfa are considered superior (don't really know why anymore lol)... beta are more neutral....
1. If only omega can get pregnant, doesn't that mean only omega have wombs? In that case, they can't tell the gender from birth (like ultrasounds)? Actually, if it is just a blood test, why don't they do it from birth?
2. Heat just happens to start after the test? If it was anything like real world puberty, you'd get some kids already having their heat even before the test and lecture. It seems silly that after the test suddenly everyone starts showing signs of their gender.
3. If only omega can get pregnant, that means everyone's mom is an omega. In that case, why do they have the nerve to discriminate? Dx It doesn't make sense. The only way it makes sense is if the translators meant omega men and all women. So anyone would two men as parents would know on is omega. Anyone with a male and female parents wouldn't know if their mom is omega, alpha, or beta.