Source: Ismaili Gnosis
Prophet Muhammad married 12 women over his lifetime: 1 marriage was for love (Khadijah); 6 marriages (Sawda, Hafsah, Zaynab, Umm Salamah, Umm Habibah, Maymunah) were to vulnerable widowed and divorced women whom Muhammad took into his house and protection; 2 marriages were proposed or requested by the women (Safiyyah, Zaynab); 2 marriages were to form familial and political alliances with another tribe (A’isha, Juwariyah); 1 marriage (Maryam the Copt) was to a slave girl sent to Muhammad by the Archbishop of Alexandria (more on Muhammad’s marriages here).
•Contrary to popular myth, A’isha was not six years old when she married Muhammad. All of the historical evidence when examined as a whole suggests that A’isha was born 4 years before Muhammad began his prophetic mission and was married to the Prophet on her father’s initiative in the tenth year of Muhammad’s mission – she was therefore around 14 years of age at the time and this was a normal marriage age until quite recently. Ismaili Gnosis has summarized the evidence from various Muslim historical sources and reports which shows that she was 18 years old at marriage.