As Muslims and as sensible human beings who trust that this universe functions according to a fixed, well-designed system, we should believe that nothing happens haphazardly or aimlessly. Rather, everything is well-planned and sorted out. We read in the Quran what means:
As we have limited minds and limited spiritual abilities, we are not able to understand the wisdom behind everything in this universe. This inability to understand sometimes proves to be very important because such things will constitute a test of our faith and submission to Allah, and our trust in His infinite knowledge.
Any mature woman who has experienced menses knows what type of physical suffering a woman goes through while she is experiencing her monthly period. This is neither funny nor a nice experience. Woman has to face a lot of hormonal changes along with the pain. She has to experience emotional and physical imbalances which made her weak and fragile. It is a healthy thing for women to have this, but not every healthy thing is nice or easy. When you are ill, you have to take your medication, even if it’s bitter. Taking all such physical and mental pain into consideration, Almighty Allah, Who takes care of His servants even more than their own parents, has lifted the load of prayer and the burden of fasting from woman’s shoulders during this period.
We all know that Islam is not a difficult religion. It's we who have made this hard for us. Infect, Islam removes harm and difficulty from people's lives. As, this is mentioned in Quran in a lot of places that Almighty Allah does not intend to place any difficulty on the shoulders of His servants. Scholars summarize this in great maxim that " Difficulty Comes With Ease ", which mean when a person is experiencing anything difficult, Islam will give him some reductions that make life easy for him. Under this maxim, we can understand why a traveler is exempted from fasting, why a sick person is allowed not to fast, why a handicapped person is allowed to observe prayer while sitting down, and why a pregnant woman or a woman who is breast-feeding is entitled to break her fasting.
So, the point is not that women are “not allowed to” pray and fast but are rather exempted from observing prayer and fasting at such times, because these two duties are difficult and demand much effort.