Will the baby be affected if I take methadone?

Yes. Don't use Methadone with pregnancy. If you are or have, inform your obstetrician immediately. You may need to see a maternal-fetal specialist in consultation and you may need a high risk nursery specialist at delivery.
Yes. Any baby born to a mother on chronic opioids will be dependent on the medication when born, just like an adult. It is very rare that I recommend staying on opioids during pregnancy. There is some newer research that correlates opioids in general to increase birth defects.