It is important to note that if the aborted foetus is formed at the time of the abortion (spontaneous or otherwise), then the woman takes the same rulings as that of bleeding after childbirth. However, if the foetus is not formed, the woman can resume Prayer straight away after the abortion and wear a sanitary pad unless there is menstrual blood, in which case she applies the rules concerning menstruation.
Dr. Sa`d ibn `Abdul-`Aziz Ash-Shuwairikh, professor at the University of Imam Muhammad ibn Sa`ud, we read: “A woman who has an abortion does not take the same ruling as that of a woman experiencing post-partum bleeding unless she delivers a foetus that is formed (that is, it has limbs or facial features). If the foetus is formed when delivered, the woman takes the same rulings as that of a woman bleeding after childbirth, meaning that she is not to resume Prayer until the bleeding has stopped. Here, it is important to note that the minimum period of post-partum bleeding is one moment and the maximum duration is 40 days. If the bleeding stops after one moment and the woman is sure of her ritual purity, she can resume Prayer.
In the case when the foetus is not formed, a woman is not considered to be experiencing post-partum bleeding, so she can resume Prayer right away and wear a sanitary pad, unless the blood is menstrual (and she can ascertain this from its colour or smell). In this case the rules concerning menstruation are to be applied.”