Re: Pills to delay menstruation.
You could give this a read
Taking pills to prevent period in the last ten days of Ramadaan"We do not think that she should use these pills to help her worship Allaah, because the period which happens to her is something which Allaah has decreed for the daughters of Adam. "
And this
Taking pills to prevent menses in order to observe i’tikaaf
“It is permissible to take pills to prevent menses in order to be able to do acts of worship such as i’tikaaf, ‘umrah and Hajj, but that is subject to the condition that they should not be harmful to the body”
Guess it would differ from scholar to scholar.
And Allah knows best.