It is permissible for a breastfeeding woman to break her fast, whether it is due to a reason related to her, such as weakness or lack of the necessary nutrition needed to perform her duty, or due to fear for her infant being affected by her fasting. A breastfeeding woman is regarded in the same category as a sick person.
She must make up the days she missed fasting if she is able to do so without great difficulty. If the number of days increases and it becomes difficult for her to make them up, we rule that she should feed a poor person for each day missed—based on the opinion of Ibn ῾Umar and Ibn ῾Abbās, may Allāh be pleased with them both—at a rate of fifteen dollars per day.
Fatwā issued by Dr. Khālid Naṣr