Is a Christian woman who has premarital sex and becomes pregnant considered unchaste, and therefore should not be married?

It is a condition for marriage to a Kitabiyah (a woman from the People of the Book) that she be chaste, based on the Almighty’s saying: "and the chaste women from those who were given the Scripture before you." Therefore, it is not permissible to marry a Kitabiyah who commits fornication. This ruling does not change based on different countries or if fornication is considered normal in a certain society, as what is considered is what the Sharia (definition) has stipulated. It is better for a Muslim to marry a righteous Muslim woman, due to the risks involved in marrying Kitabiyahs.