Yes, you can still fast if your menses (haidh) or post-natal flow (nifas) ends before fajar, and you have not performed the bath in time for fajar. This is because when your menses or post-natal flow has ended, it is obligatory upon you to fast.

It is similar to the case of those who are still in the state of major ritual impurity (junub) when fajar arrives. Their fasts are still considered as valid. The basis for this ruling is in the Holy Quran: “…And eat and drink until the white thread of the dawn becomes distinct from the black thread; then complete the fast up to the night....” (Surah Al-Baqarah verse 187).

If Allah s.w.t. allows a husband and wife to have marital relations up till fajar, it means that it is allowed to perform the ghusl after fajar.

1 question

If my menses (haidh) ends before fajar, and I do not have time to perform the purificatory bath (ghusl), can I still fast?