An intrauterine abstinence syndrome (IAS) is a potentially fatal consequence of maternal opiate withdrawal. This study reviews the evidence for this syndrome. Withdrawal also creates an adverse environment for the developing fetal brain that can have long-term health effects. Effective methadone treatment eliminates risks of fetal withdrawal. However, concerns about neonatal abstinence syndrome (NAS) in methadone-exposed neonates have resulted in efforts to withdraw women from methadone during pregnancy or to use buprenorphine, a mixed agonist/antagonist opiate in place of methadone. Both approaches necessarily expose the fetus to either acute or chronic withdrawal. Routine fetal monitoring is not able to detect such symptoms, unless they are life-threatening. Therefore, the safety of the fetus during buprenorphine inductions or methadone tapers cannot be assured and the fetus should be protected from such procedures. Further research into methods of diagnosing IAS and its developmental consequences is needed to assure that attempts to reduce NAS do not harm the fetus.