It wasnarrated that Anas bin Malik said:
"The Messenger of Allah(ﷺ)granted a concession to pregnant women who fear for themselves,allowing them not to fast, and to nursing mothers who fear for theirinfants." (FR)
English reference (FR): Vol. 1, Book 7, Hadith 1668 (FR)
Arabic reference (FR): Book 7, Hadith 1737 (FR)