Question Summary:
Is the fast of a woman who gets her periods while fasting invalidated?

Question Detail:

Is a fast rendered invalid if we get periods even five minutes before Iftar? And if its invalidated then can we eat and drink?
Is it compulsory to keep the qadhaa of fasts missed due to periods before the next Ramzan?

Answer :

In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykumwa-rahmatullāhiwa-barakātuh.
1. In principle, the fast of a woman who experiences Haydh (Menstruation) for any period of time while fasting is invalidated. Moreover, the Fuqaha have stated that it is Wajib (Necessary) for such a woman to abstain from eating and drinking during the fasting time.[1]
2. It is not compulsory for a woman to fulfill the Qadha fasts missed due to Haydh (Menstruation) before the next Ramadhaan. However, it is recommended for such a woman to fulfill her Qadha fasts as soon as possible.[2]
And Allah Ta’āla Knows Best                                       
Mufti Ismail Desai,                                                                      
Darul Iftaa
Durban, South Africa
Checked and Approved by,
Mufti Ebrahim Desai.