They were no doctors, but after obtaining so much magical knowledge, Leon and Ilyana could just by feeling if the baby's condition could change. Knowing that Ilyana didn't slow down on her training. In fact, she was so eager to get stronger than she forced Leon and herself to do nothing those months aside from summoning monsters and then use Health Link, Mana Link, and Stamina Link on them.
However, both of them stopped when Ilyana gave birth to a girl that resembled her quite a bit. It looked like Ilyana's blood was strong, and the girl only had inherited from Leon his deep-brown eyes.