Does a woman expiate for her oath if she swore while she was menstruating or in postpartum bleeding?

There is no harm for a menstruating woman or a woman in postpartum bleeding (nifas) to swear by Allah the Almighty. She must offer expiation (kaffarah) if she breaks her oath, because she is not prohibited from mentioning the name of Allah the Almighty. Rather, she is only prohibited from reciting the Quran according to most scholars.