What is the ruling on menstruation for a pregnant woman?
Chapter on Menstruation
Al-Mughni
Book of Purification
Primary text
The opinion of Abu Abdullah (Ahmad ibn Hanbal) is that a pregnant woman does not menstruate; any blood she sees is blood of corruption. This is also the position of the majority of the Tabi'in, including Sa'id ibn al-Musayyab, 'Ata', Al-Hasan, and Abu Hanifa. A narration attributed to 'A'ishah supports this, indicating that if she sees blood, she does not pray. The evidence supporting this view is the Prophet's saying, which established the cessation of menses as the sign of uterine purity before intercourse, implying pregnancy and menses do not coexist. Furthermore, pregnancy is a time usually devoid of menstruation, like menopause.
Supporting text
Malik, Al-Shafi'i, and Al-Layth hold that any blood seen by a pregnant woman is menstruation, provided it aligns with a possible habit, viewing pregnancy as not precluding menses like non-pregnant women. They cite that pregnancy serves as a sign of non-menses when seeking to divorce a woman, similar to purity. They argue it is a time not usually associated with menses, and thus, blood seen then should not be menses, analogous to menopause.