Allah the Exalted clarifies the waiting period of the woman in menopause. And that is the one whose menstruation has stopped due to her older age. Her `Iddah is three months instead of the three monthly cycles for those who menstruate, which is based upon the Ayah in (Surat) Al-Baqarah. ﴿see 2:228﴾ The same for the young, who have not reached the years of menstruation. Their `Iddah is three months like those in menopause. This is the meaning of His saying;

﴿وَاللَّـتِي لَمْ يَحِضْنَ﴾

(and for those who have no courses...) as for His saying;

﴿إِنِ ارْتَبْتُمْ﴾

(if you have doubt...) There are two opinions: First, is the saying of a group of the Salaf, like Mujahid, Az-Zuhri and Ibn Zayd. That is, if they see blood and there is doubt if it was menstrual blood or not. The second, is that if you do not know the ruling in this case, then know that their `Iddah is three months. This has been reported from Sa`id bin Jubayr and it is the view preferred by Ibn Jarir. And this is the more obvious meaning. Supporting this view is what is reported from Ubay bin Ka`b that he said, "O Allah's Messenger! Some women were not mentioned in the Qur'an, the young, the old and the pregnant.'' Allah the Exalted and Most Honored sent down this Ayah,

﴿وَاللاَّئِى يَئِسْنَ مِنَ الْمَحِيضِ مِن نِّسَآئِكُمْ إِنِ ارْتَبْتُمْ فَعِدَّتُهُنَّ ثَلَـثَةُ أَشْهُرٍ وَاللَّـتِي لَمْ يَحِضْنَ وَأُوْلَـتُ الاٌّحْمَالِ أَجَلُهُنَّ أَن يَضَعْنَ حَمْلَهُنَّ﴾

(Those in menopause among your women, for them the `Iddah, if you have doubt, is three months; and for those who have no courses. And for those who are pregnant, their `Iddah is until they lay down their burden.) Ibn Abi Hatim recorded a simpler narration than this one from Ubay bin Ka`b who said, "O Allah's Messenger! When the Ayah in Surat Al-Baqarah was revealed prescribing the `Iddah of divorce, some people in Al-Madinah said, `There are still some women whose `Iddah has not been mentioned in the Qur'an. There are the young, the old whose menstruation is discontinued, and the pregnant.' Later on, this Ayah was revealed,

﴿وَاللاَّئِى يَئِسْنَ مِنَ الْمَحِيضِ مِن نِّسَآئِكُمْ إِنِ ارْتَبْتُمْ فَعِدَّتُهُنَّ ثَلَـثَةُ أَشْهُرٍ وَاللَّـتِي لَمْ يَحِضْنَ﴾

(Those in menopause among your women, for them the `Iddah, if you have doubt, is three months; and for those who have no courses.)''