Description

• Neonatal abstinence syndrome (NAS) occurs due to intrauterine exposure to maternal opioid medications (whether the mother is on maintenance opioid therapy, using illicit opioids, or abusing licit opioids), causing a postnatal withdrawal syndrome.
• Signs of NAS include gastrointestinal (GI) tract dysfunction, central nervous system (CNS) irritability, and autonomic overreactivity following birth secondary to a lack of maternal drug supply.
• Iatrogenic drug withdrawal syndrome may be seen in infants and children treated with opioids (following severe illness or surgery with similar symptoms) but is not the focus of this chapter.

Epidemiology

Risk Factors

Maternal: Chronic pain, medication-seeking behaviors, opioid maintenance therapy, report of drug abuse, multidrug use (e.g., nicotine, benzodiazepines, trazodone, SSRIs), homelessness, history of sexual abuse, or domestic violence

• 4.5% of pregnant women age 15 to 44 years reported recent use of illicit drugs.
• 6% of mothers reported use of prescription opioids for >1 month of pregnancy.

General Prevention

• Prenatal education and counseling of at-risk women
• Prenatal treatment—opioid maintenance therapy
• Prevention of abrupt drug cessation during pregnancy

Pathophysiology

• Opiates are low-molecular-weight, water soluble, lipophilic compounds that easily cross placenta, increasingly as gestation progresses.
• Opioids easily cross fetal blood–brain barrier.
• Opioid receptors are extensive in CNS as well as the peripheral nervous system, GI tract, and other organ systems.
• Opioids have a prolonged half-life in fetus.
• Neonatal neurobehavioral dysregulation is the major manifestation of NAS.

Etiology

Intrauterine exposure to maternal licit or illicit opioid use, with cessation of the exposure at clamping and cutting of the umbilical cord

Commonly Associated Conditions

• Premature birth
• Placental abruption
• Poor intrauterine growth and/or small for gestational age
• Feeding problems
• Seizures (uncommon)
• Birth defects (rare)