Neonatal Abstinence Syndrome (NAS) – What is NAS?
Neonatal abstinence syndrome (NAS) is a group of problems that occur in a newborn who has been exposed to addictive illegal or prescription drugs. Prenatal NAS results from the sudden discontinuation of fetal exposure to substances that were used by the mother during pregnancy. It is often a multi-system disorder that frequently involves the CNS, GI system, autonomic system, and respiratory system. Symptoms of NAS depend on various factors including the type of drug the mother used, how much of the drug she used, how long she used the drug, and how the mother’s body breaks down the drug. Maternal substance abuse, the cause of NAS, is a leading preventable illness of mental, physical, and psychological problems in infants and children. Substance use by pregnant women has both medical and developmental consequences for newborns, in addition to the legal, health, and economic consequences for the mother. Most illicit drugs cause addiction for the mother and dependence in the infant.
Dependence or tolerance in the infant is a result of the passage of drugs across the placental barrier. Substances that act on the central nervous system easily cross the placenta allowing a rapid equilibration of drugs between the mother and the developing fetus. They accumulate in the fetus because of the immature systems that are needed for metabolism of the drug. Child birth removes the drug source resulting in withdrawal. The symptoms and timing of the withdrawal depends on the drug, the frequency of maternal use, the last exposure for the fetus and the baby’s ability to metabolize the drug. The specific effects of illicit substances are complex and depend on the type of substance. Opiates produce the most dramatic effects on both the mother and fetus because of its short half-life. Heroin withdrawal may start as early as 24 hours after birth and usually peaks within 48-72 hours in 50-80% of infants.
Infants who had prenatal exposure to buprenorphine required significantly less morphine for the treatment of NAS, a significantly shorter period of NAS treatment, and a significantly shorter hospital stay than did infants with prenatal exposure to methadone. Long-term problems of children exposed to illicit drugs in the womb include adverse neurodevelopmental outcomes. Speech, perceptual, memory and reasoning disturbances have been reported in toddlers who were exposed to opiates. Behavioral problems are also reported in children of mothers who have taken illicit substances in pregnancy.
Others reported lower levels of learning and adapting to new situations; higher sensitivity to their environment; resulting in irritability, agitation, aggression, poor social skills; and a lack of imitative play and late emergence of symbolic play. Prognosis widely varies and depends on the family, socioeconomic variables, and whether either or both parents continue to use illicit drugs. Children of mothers ceasing or decreasing their use of substances up to time of the birth delivered healthier babies than the mothers who continued to use substances. In addition, their results indicated that early intervention, including treatment of addiction during pregnancy, prenatal care, and psychosocial support, helped to prevent some developmental defects of newborn children of substance-using mothers. MAT has also been shown to decrease illicit behaviors, improve prenatal care and obstetric outcomes resulting in improved family outcomes.
Pregnant drug-using women should be counseled at the earliest opportunity to abstain completely from all injurious substances, enter into a comprehensive treatment program, be provided smoking cessation options and seek prenatal care. Adequate dietary intake and early supplemental prenatal vitamins with folic acid should be stressed. Ideally, illicit substance use including tobacco should be terminated by women and their male sexual partner before conception. Prevention is the best way to stop NAS.
Some delayed withdrawal can occur as long as 6 days after birth. Sedative-hypnotics such as benzodiazepines and barbiturates have a longer half-life and withdrawal may not start until after the infant has been discharged from hospital (age 2 weeks). Methadone maintenance has been an acceptable form of therapy for opiate-addicted pregnant women for more than 20 years. Methadone is currently the recommended treatment for opioidaddicted pregnant women and is considered relatively safe for the fetus. Medically however, it is also associated with NAS, and its effects on the fetus are similar to the effects of heroin. Methadone’s half-life is longer than 24 hours, and acute withdrawal may occur within the first 48 hours after birth and as long as 7-14 days later. The withdrawal can be delayed for as long as 4 weeks after birth, with subacute signs developing as long as 6 months after birth. Buprenorphine has recently been approved for treating opioid addiction. Buprenorphine and methadone have comparable maternal efficacy although methadone seems superior in terms of retaining patients in treatment.
Dr. Jones is the founder and CEO of Mango Bay Retreat, a premier addiction facility for women, specializing in pregnant women.