The date of definition must be accepted by all faithful members of the Catholic Church as contained specifically in the Deposit of Faith and owed supernatural faith in itself (de fide credenda).
There are four Marian dogmas specifically defined by the Magisterium among a large number of other dogmas and doctrines about the Virgin Mary - for example, the Annunciation of Mary is dogma because it is in the scriptures, but it has not been specifically defined by the Magisterium.
These four Marian dogmas include: Mother of God, not that the nature of the Word or his divinity received the beginning of its existence from the holy Virgin, but that, since the holy body, animated by a rational soul, which the Word of God united to himself according to the hypostasis, was born from her, the Word is said to be born according to the flesh.
Although there are only four Marian dogmas, popular support for a "fifth Marian dogma" which establishes Mary as Co-Redemptrix and Mediatrix appeared in the 20th century both from lay groups and the clergy.
However, a number of other Catholic doctrines about the Virgin Mary have been developed by reference to sacred scripture, theological reasoning and Church tradition.