Ask or doctor about Subutex NOT methadone. It does the same thing but more than likely when the baby is born it will not have withdrawals. Methadone is a trap and the hardest thing to come off of. But the mainthing is talk and be honest with your doctor
Tell your doctor asap so you can start taking methadone. The withdrawals may harm your baby and for that reason most likely be put on methadone. Sadly your baby will be born addicted to it and go through withdrawals too. I wish you the best of luck.
When is your first appointment? Talk to your doctor about your concerns they should be able to provide you with resources. You can also search for a help group and they should be able to provide you with information as well.