The main character has a womb despite being a man. That's also the reason his father despises him because he is a "freak" according to the father. So when he did it with the same, he ended up pregnant since there was no protection and stuff.
Xi nian has a uterus. He had a genetic problem. "Hypothetically ", but sciantifically there really is a sickness with those gene problem who has uterus but they can't bore a child. But in this story they could. So yeah. Its fantasy
I am really confused as to how Wo Wo was born. Did I miss it? Can anyone tell me?