Must a woman who miscarried her fetus in the early days of Ramadan fast, while the miscarriage process, bleeding, and pain continue?

If the blood of an abortion shows the formation of a human being—the minimum period for which to be discernible is 81 days—then it is nifas blood (postnatal bleeding) which prohibits prayer and fasting. If the formation of a human being is not discernible—for example, if the pregnancy was 6 weeks old—then it is istihadah blood (irregular vaginal bleeding), which does not prohibit prayer and fasting unless it coincides with the menstrual period.