Neonatal Abstinence Syndrome (NAS) is a general medical term to describe infants that were prenatally exposed to narcotics. BAbies with NAS have their digestive, respiratory and nervous system affected. During pregnancy drugs are passed from the mother to the fetus via the placenta and surpass the blood/brain barrier. Exposure to the fetus cause the unborn child to also become addicted to the substances they are exposed to. The baby is then born addicted to said substances. Not all babies born to women addicted to illicit substances go on to experience withdrawal symptoms. According to Standfordchildrens.org "Opiates, such as heroin and methadone, cause withdrawal in over half of babies exposed prenatally. Cocaine may cause some withdrawal, but the main symptoms in the baby are due to the toxic effects of the drug itself."
Symptoms often do not present at birth but take 24 hours to days later to present. In Baby Girls case it was a few days after her birth that she experienced symptoms and D was lead to believe that she was out of the window of risk when she presented with symptoms (I believe she presented with symptoms on day 3). Accordin to Standforchilderens.org symptoms that an NAS baby may present with are "tremors, irritability, sleep problems, [a distinct] high pitched cry, [high] tone, hyperactive reflexes [specifically the startle reflex], seizures, yawning, poor feeding/suck, vomiting, diarrhea, [diaper rash], dehydration, sweating, and fever or unstable temperature."
NAS is diagnosed based on their symptoms which are scored using the Finnegan NAS Score. According to http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0004566/ a toxigology report can be obtained from the first stool. A verbal history and toxicology report of the mother also can be used to monitor the baby for symptoms of withdrawal. Though several sources reported that mothers are likely to underreport exposures. D's verbal report was inconsistent between the medical chart and her adoption paper work. The symptoms that Baby Girl presented with were not consistent with the verbal report from D provided the medical staff; which likely means Baby Girl had more exposures than we initially were told about.
There is also questions in the literature if it is appropriate to state the baby is born "addicted" as the fetus was subjected to an exposure and was not a willing participate. "Prenatally exposed" appears to be an accepted term.