i dont remember is it a manga, manhua, or manhwa.
the story i remember was female knight or princess fighting the enemy, but get stabbed on abdoment.Her life was in danger. Then the princess was taken to some room. In the room, there is three or four people i think a doctor want to save the princess. But they make conclusion that to save the princess life they must take away the uterus. If they take the uterus then the princess cannot have a children and the kingdom in danger because didn't have a heir. Then mc ( i don't remember is he reincarnated or not) hear the talk and then went to the room. The doctor is angry to mc because he enter the room without permission. Mc talk to the doctor that he can save the princess and her uterus. But everyone else must go outside. The doctor ask mc how can he save the princess life but mc answer he can but cannot show it to anyone else. Then the doctor go outside. I don't remember how mc save the princess life. In the next day, princess thanks to mc after saving her life and didn't have to lose her ability to have children.