APA Dictionary of Psychology

a syndrome in which a newborn is born with physiological, neurological, and/or behavioral signs of drug withdrawal due to intrauterine exposure to addictive drugs, such as opioids. Clinical signs in infants diagnosed with the syndrome, more commonly called neonatal abstinence syndrome (NAS) or neonatal withdrawal syndrome (NWS), include increased risk of intrauterine mortality, preterm birth, low birth weight, hyperactive reflexes, tremors, irritability, sleep problems, and increased risk of neonatal mortality.