I know you are trying to do the right thing, but please talk to your doctor. It's unfair to your baby not to. If you're honest with your doctor and stay on the plan your baby will be ok and you won't have the fear of him or her being taken away! It's when you aren't honest that things get hairy. I'm sure you're scared. Do the right thing and keep us updated.
Your best bet is to talk with your OB about it but I will post some info below for you.
Standard Protocol
When a pregnant woman wants to detoxify from opiates or other opioids, the recognized standard of care, according to the National Health Institute, is methadone treatment while under a doctor's supervision. Methadone is not known to cause birth defects nor have any long-term affects on a baby. There are other medications available for opiate detoxification such, as Suboxone (buprenorphine/naloxone), or Subutex, (buprenorphine), but because they are "Pregnancy Category C" medications, meaning they are known to cause harmful and possibly fatal birth defects on a fetus, the are not recommended for use in detoxifying pregnant women.
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"If a mother stops using the drug "cold turkey," the fetus will then experience withdrawal symptoms in the womb, with may cause wide swings in the baby's blood level from intoxication to withdrawal, which often times leads to death and spontaneous abortion, premature birth, and other negative effects. The best thing for the mother to do would be to consult a health care provider or drug treatment center about a methadone program, which will be less harmful for the baby."