The discharge which is passed continuously by a woman does not have any effect on the fast
This kind of discharge is passed a great deal by women. It is taahir (pure) and not naajis (impure), and there is no need to do ghusl because of it. All it does is invalidate wudoo’.
Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) was asked about it and he replied:
After researching the matter, it seems to me that the discharge that is passed by women, if it does not come from the bladder but rather from the womb, then it is taahir…
This is the ruling on this discharge with regard to tahaarah (purity) – it is taahir and does not make the clothes or the body naajis.
With regard to wudoo’, the ruling is that it invalidates wudoo’, unless it is continual, in which case it does not invalidate wudoo’, but the woman should not do wudoo’ for each prayer until after the time for the prayer has begun, and she has to use a pad.
But if it starts and stops, and it usually stops at the time of prayer, then she should delay the prayer until the time when it stops, so long as there is no fear that the time for prayer will end. If she fears that she will miss the prayer, then she should do wudoo, use a pad and pray. It makes no difference if there is a little or a lot, because it is all coming from the front passage so a little or a lot invalidates wudoo’.
Majmoo’ Fataawa Ibn ‘Uthaymeen, 11/284
Using a pad means placing a piece of rag or cotton etc in the vagina so that less of this discharge will come out, and to prevent it getting on to the clothes or body.
Based on this, there is no need to do ghusl because of this discharge, and it does not affect the fast. With regard to prayer, wudoo’ must be done for each prayer after the time for the prayer has begun, if the flow is continual.
And Allaah knows best.