Surah At-Talaq, ayah 4

وَٱلَّٰٓـِٔي يَئِسۡنَ مِنَ ٱلۡمَحِيضِ مِن نِّسَآئِكُمۡ إِنِ ٱرۡتَبۡتُمۡ فَعِدَّتُهُنَّ ثَلَٰثَةُ أَشۡهُرٖ وَٱلَّٰٓـِٔي لَمۡ يَحِضۡنَۚ وَأُوْلَٰتُ ٱلۡأَحۡمَالِ أَجَلُهُنَّ أَن يَضَعۡنَ حَمۡلَهُنَّۚ وَمَن يَتَّقِ ٱللَّهَ يَجۡعَل لَّهُۥ مِنۡ أَمۡرِهِۦ يُسۡرٗا ٤

Wallā'ī ya'isna minal-mahīdi min nisā'ikum inirtabtum fa'iddatuhunna thalāthatu ashhurin wallā'ī lam yahidna wa ulātul-ahmāli ajaluhunna an yada'na hamlahunna waman yattaqillāha yaj'al lahū min amrihī yusrā

And those who no longer expect menstruation among your women - if you doubt, then their period is three months, and [also for] those who have not menstruated. And for those who are pregnant, their term is until they give birth.¹⁷⁰⁰ And whoever fears Allāh - He will make for him of his matter ease.