All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
If a child entered the state of Ihraam independently, in case he was discerning, or if the intention of entering it was made on his behalf by his guardian if the child was under the age of discernment, then he is treated in the same way as an adult concerning the actions that are forbidden in Ihraam.
A boy, in the state of Ihraam, should not wear stitched clothing such as trousers and a girl should not wear Niqaab or gloves.
As for wearing trousers by girls beneath her clothes, other than in a state of Ihraam, or by a little girl who is not aroused sexually by wearing them, then there is no problem in wearing them. If she is grown up and wearing them may arouse sexual desire, then she should not wear them except beneath her clothes because wearing it uncovered shows the details of her body, reveals her beauty and draws people's sight toward her which incurs sin on their part.