Is it permissible for a pregnant and breast-feeding woman not to fast?
Enes Ibn Malik (R.A.) quotes the Prophet as saying: “Undoubtedly Allah has relieved the travelers of fasting and half of the prayer, and the pregnant and the breast-feeding women of the fast." (Abu Dawud, Sawm: 44, Tirmidhi, Sawm: 21; Ibn Majah Sıyam: 12)
If pregnant women and breast-feeding mothers cannot endure fasting, they don’t have to fast in the month of Ramadan. They can perform their missed fast(s) without any necessary order at a reasonable time after Ramadan.