A Muslim woman is not permitted to fast in Ramadan if she is menstruating. However, after the blessed month, she has to make up for the missed days of fasting due to menstruation. If a woman wants to take pills to delay menstruation during the blessed month in order to be able to fast and pray along with the other Muslims, she is permitted to do so as long as the pills are taken under the supervision of a physician and there is no harm to her health.
Sheikh Yusuf Al-Qaradawi states the following: Muslims have unanimously agreed that a Muslim woman who menstruates in the blessed month of Ramadan is not to observe fast during her period. That is to say, she is not to observe the fasts in question during the month itself, but she must make up for these days after Ramadan. This is an alleviation and a mercy from Allah for the menstruating woman, as her body becomes tired and she feels tense. She must break fast as an obligation and not as a mere legal act that she is permitted to do. Thus, if she observes fast, her fasting will not be legally sufficient, nor will it be accepted from her. Accordingly, she must make up for this by observing fast for a number of days instead of the days in question.
This is what Muslim women have always done since the era of the mothers of the Believers and the female Companions (may Allah be pleased with them all), and those who followed them in goodness. Hence, if a Muslim woman has her period during Ramadan, there is no harm if she breaks her fast and makes up for it after Ramadan. It has been reported that `A’ishah said, “We would be commanded to make up for (the unobserved) fasting yet we were not commanded to make up for (the unperformed) prayers” (Al-Bukhari).
I personally prefer that people let things go naturally. Since menstruation is a natural thing that keeps up with fitrah (natural disposition), let it be as natural as it has been made by Allah, Glorified and Exalted be He.
Yet still, if there is some kind of pill or drug that a woman may take to delay her menstruation in order not to break the fast in Ramadan, there is no harm in doing this. But she must make sure that this will not harm her by consulting a specialized physician. Therefore, if she makes sure of this, takes the pills, and her menstrual period is delayed and she observes fast, her fasting will be acceptable, in sha’ Allah