Pregnancy changes the way an orthodontic patient is monitored. Special attention needs to be paid to the condition of the gums, and any discomfort caused by the appliance should be kept to a minimum where possible. It's best to let your orthodontist know about a pregnancy as soon as you find out. Of course, this means postponing any procedures that aren't urgent and require local anaesthetic.
This answer is for general information. Your own case needs an examination by an orthodontist.