"Little Sister Xiulan, don't forget that your body went through a lot to survive from that car crash when you were only eighteen," Long Jinjing reminded Iris. "Because of that evil woman Fan Luo, you almost died. It's already a miracle that you're still alive and well today and even pregnant with my niece or nephew. I don't think that your body is failing you. Maybe it's just dealing with any remaining sequelae from the injuries you sustained from that car crash."
Iris and Lu Zihao didn't refute Long Jinjing's claim, although both of them knew that the original Iris Long really died during that fatal car crash. However, it was indeed a miracle that another soul occupied the original's body and began living as the new Iris Long. Perhaps Long Jinjing might be right—that there were still some remaining sequelae in Iris' body that the doctors couldn't detect. This might be why the body couldn't keep keep pace with the many things that Iris, no, that Evelina wanted to do.