What are the postnatal and prenatal causes of neonatal abstinence syndrome (NAS)?

Updated: Dec 20, 2017
  • Author: Ashraf H Hamdan, MD, MBBCh, MSc, MRCP, FAAP; Chief Editor: Santina A Zanelli, MD  more...
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Answer

Postnatal NAS results when an abrupt discontinuation of opioid analgesia occurs, usually after prolonged drug exposure. Fentanyl is the most commonly used analgesic drug in the neonatal intensive care unit (NICU). It is a potent, rapid-acting, synthetic opioid with a relative lack of hemodynamic side effects. Clinical studies have found that continuous infusions of fentanyl and morphine produce a high rate of opioid withdrawal when administered to critically ill infants. Tolerance and physical dependence are thought to develop more rapidly with shorter acting drugs and after continuous infusions rather than with intermittent administration. Tolerance and withdrawal symptoms may occur after 5 or more days of continuous infusion of fentanyl. This occurs more often with fentanyl than morphine. [3, 4] This article focuses on prenatal or maternal use of licit or illicit drugs, although symptoms and therapy for postnatal NAS are similar.

Maternal substance abuse, the cause of prenatal NAS, is a leading preventable cause of mental, physical, and psychological problems in infants and children. Substance use by pregnant women has both medical and developmental consequences for the newborn, in addition to the legal, health, and economic consequences for the mother.


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