Reference: Fataawa at-Talaaq – Question 24, Page 48
Question: Is it permissible to divorce a pregnant woman or not?
Response: There is no harm in divorcing a pregnant woman, as the Prophet ﷺ said to ‘Abdullaah ibn ‘Umar when he divorced his wife whilst she was on her menses:
«Take her back, and hold on to her until she becomes pure then comes on her menses, then becomes pure, then divorce her if you wish, whilst she is in a state of purity or pregnant, before you touch her».