Nowhere in the Quran does it say that women cannot fast, pray, or worship in any other way during their menstruation. This is an innovation. We have to know that any rule telling us NOT to worship God under this or the other circumstance must be from Satan, not from God.
The verse they base this false idea about women not being able to pray or fast during menstruation is 2:222. They claim that it says that women are unclean during menstruation, and therefore cannot be allowed to pray.
Let us read this verse carefully, as God tells us to (4:82), to determine if this is really what it says.
[2:222] They ask you about menstruation: say, "It is harmful; you shall avoid sexual intercourse with the women during menstruation; do not approach them until they are rid of it. Once they are rid of it, you may have intercourse with them in the manner designed by GOD. GOD loves the repenters, and He loves those who are clean."
The first part of this verse teaches us that it's harmful to have sexual relations during menstruation. If you ask any doctor, Muslim or not, about having intercourse during this period, he or she will tell you that it's harmful for both the man and the woman.
Now let's look at the second part of this verse, which deals with the period after "they are rid of it." Then we are told, the men may have intercourse with the women "in the manner designed by God." Would God need to tell us about "the manner designed by God," if there we no other manner by which to have intercourse? No. There is another way, which is not approved by God. This is why the verse ends by saying that God "loves those who are clean."
If we haven't gotten the point by now, the next verse is quick to remind us which manner is approved. It starts by saying, "Your women are the bearers of your seed." There is only one way that a woman can bear the mans seed. The verse continues again to remind the men that they may enjoy this privilege "as long as they maintain righteousness."
[2:223] Your women are the bearers of your seed. Thus, you may enjoy this privilege however you like, so long as you maintain righteousness. You shall observe GOD, and know that you will meet Him. Give good news to the believers.
Nowhere in the Quran does it say that women cannot fast, pray, or worship in any other way during their menstruation. This is an innovation. We have to know that any rule telling us NOT to worship God under this or the other circumstance must be from Satan, not from God. The only thing prohibited during menstruation is sexual intercourse as given in 2:222. But the ignorant use this verse to base this false idea about women not being able to pray or fast during menstruation. They claim that it says that women are unclean during menstruation (2:22), and therefore cannot be allowed to pray.
As analyzed above, 2:222 does not prohibit a women from observing the religious duties during menstruation, but only restricts sexual intercourse during such times. The only circumstances that makes us unclean in the eyes of God, when it comes to performing the prayers are mentioned in 5:6 and 4:43. In none of these verses does it say that menstruation is one of these circumstances. All we have to do to clean ourselves for Salat, is to perform the Wudu. However there is an incorrect understanding that menstruation nullifies ablution. But this again does not have any support in Quran. There are two verses in Quran that tells us what nullifies ablution; 4:43 and 5:6.
[4:43] O you who believe, do not observe the Contact Prayers (Salat) while intoxicated, so that you know what you are saying. Nor after sexual orgasm without bathing, unless you are on the road, traveling; if you are ill or traveling, or you had urinary or fecal-related excretion (such as gas), or contacted the women (sexually), and you cannot find water, you shall observe Tayammum (dry ablution) by touching clean dry soil, then wiping your faces and hands therewith. GOD is Pardoner, Forgiver.
[5:6] O you who believe, when you observe the Contact Prayers (Salat), you shall: (1) wash your faces, (2) wash your arms to the elbows, (3) wipe your heads, and (4) wash your feet to the ankles. If you were unclean due to sexual orgasm, you shall bathe. If you are ill, or traveling, or had any digestive excretion (urinary, fecal, or gas), or had (sexual) contact with the women, and you cannot find water, you shall observe the dry ablution (Tayammum) by touching clean dry soil, then rubbing your faces and hands. GOD does not wish to make the religion difficult for you; He wishes to cleanse you and to perfect His blessing upon you, that you may be appreciative.
These verses that explain what nullifies ablution are applicable to both men and women. We learn from the above verses that the excretion should be both fecal related and a digestive excretion to nullify ablution.
Accordingly, menstruation does not nullify ablution. Please ask yourself why can't you accept that women could observe her religious duties of praying or fasting, etc during menstruation. Is it God's laws that impose such prohibitions? Or is it a baseless prohibition instituted by religious scholars, erroneous religious laws inherited from our ancestors that have no Quranic back-up, etc. The answer you get will never have God's support. Women's menstruation is by God's design. Why should women be restricted from worshipping God during times which is exactly as designed by Him, for which she has no control?