My wife has seen a dream revealing she was pregnant and the baby's name was Mariam. After she had seen the dream she was pregnant and the doctor reckons she has a girl. Is it haram to change the name and also please advice me and tell me is it a dream we have to fulfill.
Dreams can have any meaning. The interpretation of a dream itself is a very, very difficult process. But in dream interpretation (or its science), there is nothing like you MUST follow a dream.
So there is nothing like an obligation upon you to follow this dream. This dream could mean anything. Just beware of interpreting dreams based on your own limited knowledge, as it could be very dangerous.
You can notice the stated dream as a true one or not. I think there is an islamic science as the science of dreaming interpretation. Of course the point is that may be very limited percent of people can have this science. Of course there are some authentic sources or books which have illustrated about the interpretation of different items about dreams.
Besides you should note some points too. Firstly, occasionally some events take pla ce accidentaly, thus we can not attribute them to the interpretation of the dreams as two relevance matters. Secondly there are some criteria or conditions in order to interpretting the dreams correctly, in fact every dream cannot be honest. For instance it is said that the dreams which are near the salat al fajr, can be more authentic, or the dreams which are after the fajr, cannot be trusted, and other conditions that I suggest you to have some study about them as well. OF COURSE DO NOT FORGET THAT THERE IS NO OBLIGATION FOR US ABOUT DREAMS TO FOLLOW AND ACT ABOUT THEM.
Although you'd better to select that name , mariam I mean. Because it is a nice holy name anyway which can be relevance according to your dream too (but as an option u choose it, otherwise you are free to choose her name.
Dreams are figurative, images. You don't have to comply with a dream, no matter how good or bad. Dreams can be a source of inspiration, happiness or mental support.
However, there are interpretations. In particular when it is a good dream, you should smile. There is something good in it.
When it is a good dream, you can mention it. It can make people happy.
When it is a bad dream, you are not supposed to mention it and simply forget about it.
I think your dream is wonderful. Be happy, and I hope in God's name that your baby girl will bring blessings to you. Mary is a beautiful and important (Jesus' mother's name was Mary) name.