Is a marriage between a young man and a young woman, arranged with the knowledge of the young man's maternal uncle, after the young woman appointed him as her proxy due to the absence of a guardian for her, considered Islamically valid, given that the young woman is pregnant and the marriage is officially documented?

For a marriage to be valid, the presence of a guardian (wali) and two just witnesses is required. If the ruler ratifies it, it cannot be revoked. It is commendable to mention the dowry (mahr) in the contract, though the contract is valid without it, and in such a case, the wife is entitled to a dowry equivalent to that of her peers. If a specific dowry is agreed upon, that is what becomes binding.