Must a sick mother, whom the doctor has forbidden from fasting, fast Ramadan?

If fasting is harmful to the mother or causes her extreme hardship, she may break her fast and make up the days she missed if she is able. However, if she is unable to make up the days, she must feed a poor person for each day, as Allah Almighty says: "And upon those who are able to fast, but with difficulty, a ransom of feeding a poor person." The jurists disliked a sick person fasting if it harmed them, and some even mentioned that it becomes forbidden for them if they fear perishing. Indeed, some scholars even preferred that it is obligatory for a sick person who would be harmed by fasting to break their fast. However, if fasting does not cause her hardship or harm, she must fast.