Muhammad's wives
Muhammad was monogamous for 25 years. After his first wife Khadija bint Khuwaylid died, he proceeded to marry the wives listed below, and most of them were widows. Muhammad's life is traditionally delineated as two epochs: pre-hijra (emigration) in Mecca, a city in western Arabia, from the year 570 to 622, and post-hijra in Medina, from 622 until his death in 632. All but two of his marriages were contracted after the Hijra (migration to Medina). Of Muhammad's thirteen wives, at least two, Rayhana bint Zayd and Maria al-Qibtiyya, were referred to simply as concubines; however, there is debate among Muslims as to whether these two officially became his wives. Of his thirteen wives, only two bore him children, a fact which has been described as "curious" by Cornell University Professor of Near Eastern Studies David S. Powers.
Muhammad Hussain Najafi
Before going to Najaf for higher religious education, he was married to his maternal cousin in 1952. His teacher Allama Yar Shah had links with ulema of Najaf, and he wanted Muhammad Hussain to get married in a scholarly family of Najaf, but Muhammad Hussain declined this proposal due to cultural differences.
In 1954, his only son Muhammad Sibtain was born. At the age of five, he got seriously ill and died, as Muhammad Hussain did not have enough money for his treatment. (Muhammad Hussain used to spend his stipend money on household and buying books.) 
After Sibtain's death, Ayatollah Najafi did not have children for next eleven years. He married the daughter of Haji Muhammad Shafi (Faisalabad) in 1970. He had three daughters from this marriage. His first wife died in 1996.