What is the significance of the timing of onset of the symptoms and gestational age in the evaluation 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

The timing of onset of the symptoms gives an indication of the maternal drug abuse. Withdrawal from high levels of maternal alcohol can occur within a day or 2 of birth. Heroin has a short half-life and withdrawal also occurs within 48–72 h of birth, whereas methadone withdrawal occurs at 7–14 days.

Preterm infants are at lower risk of drug withdrawal with less severe courses. Infants born at less than 35 weeks’ gestation whose mothers received methadone maintenance had significantly lower total and CNS abstinence scores than did term infants of mothers receiving similar methadone dosages. [38] In a more recent study, lower gestational age correlated with a lower risk of neonatal withdrawal. [39] The apparent decreased severity of signs in preterm infants may relate to developmental immaturity of the CNS, differences in total drug exposure, or lower fat deposits of drug. [40]


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