while her husband is still alive;
5. A woman whose menstruation has ceased and she does not know the cause;
6. The wife of a man who is missing.

Here is a detailed discussion of each category.

1. A pregnant woman: her waiting period ends when she delivers the child, whether the separation occurred during the husband’s lifetime or because of his death. Allah the Exalted says, “As for those who are pregnant, their term ends when they deliver” (Qur’an 65:4). The verse clearly states that the pregnant woman’s ʿiddah terminates at childbirth in both situations. Some of the early generations maintained that a pregnant widow must observe whichever of the two periods (the pregnancy or the widow’s term) is longer, but consensus later settled that her ʿiddah ends the moment she gives birth.

Not every expelled mass, however, qualifies. The pregnancy must have developed enough for distinct human features to appear; if she miscarries an unformed lump of flesh, her ʿiddah is not over.

Moreover, the fetus must be legally attributable to the husband from whom she separated. If it cannot be—because the husband is too young to be capable of procreation, suffers from a physical impediment, or because she gives birth in less than six months from the time of the marriage contract, even though cohabitation was possible and the infant survives—then the birth does not end her ʿiddah, for the child is not ascribed to him.

The minimum gestation period is six lunar months. Allah says, “His bearing and his weaning last thirty months” (Qur’an 46:15), and He also says, “Mothers shall suckle their children for two full years” (Qur’an 2:233). Subtracting the twenty-four months of nursing from the thirty months mentioned in the first verse leaves six months, and no child born alive before that term has ever been recorded to survive.