Question Summary:
Were the wives of Rasul (Sallalahu Alahi Wa Sallam) unable to conceive?

Question Detail:

Is it true that Nabi (SAW) did not have any children from all his other wives besides Khadija, is it because the other wives couldn’t not conceive children? 

Answer :

In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
The Prophet’s (Sallalahu Alahi Wa Sallam) children were all from Khadija (Radhiallahu Anha) except Ibrahim (Radhiallahu Anhu), who was from Mariah Qibtiyyah (Radhiallahu Anha).[1]
It is not true that the other wives of Rasul (Sallalahu Alahi Wa Sallam) were unable to conceive, as some of them had children from previous marriages.[2]
Moreover, as Muslims we believe that Allah Ta’ala is the Creator and Controller of the entire universe.. He is the one who grants health, wealth, family, children, and every blessing man enjoys in this world. Allah Ta’ala in His infinite wisdom knows best the reason for doing certain things. He is ultimately the Controller of all affairs. Allah Ta’ala says in the Quran: 
لَّهِ مُلْكُ السَّمَـوَتِ وَالاٌّرْضِ يَخْلُقُ مَا يَشَآءُ يَهَبُ لِمَن يَشَآءُ إِنَـثاً وَيَهَبُ لِمَن يَشَآءُ الذُّكُورَ - أَوْ يُزَوِّجُهُمْ ذُكْرَاناً وَإِنَـثاً وَيَجْعَلُ مَن يَشَآءُ عَقِيماً إِنَّهُ عَلِيمٌ قَدِيرٌ  
To Allah belongs the kingdom of the heavens and the earth. He creates what He wills. He bestows female upon whom He wills, and bestows male upon whom He wills. Or He bestows both males and females, and He renders barren whom He wills. Verily, He is the All-Knower and is Able (to do all things).(AshShuraa 42)
 
And Allah Ta’āla Knows Best
Arshad Ali
Student Darul Iftaa
Trinidad
Checked and Approved by,
Mufti Ebrahim Desai.
http://www.daruliftaa.net/