Neonatal Adaptation Issues After Maternal Exposure to Prescription Drugs: Withdrawal Syndromes and Residual Pharmacological Effects

Exposure to drugs during pregnancy has the potential to harm offspring. Teratogenic effects are the most feared adverse outcomes in newborns; however, a wide spectrum of less known, usually reversible and often acute, neonatal adverse events can also occur due to drug intake by mothers during pregnancy, particularly in close proximity to delivery. This narrative review is aimed at the description of drugs and drug classes for which licit maternal use in the predelivery period has been associated with neonatal non-teratogenic disorders. For each drug class, epidemiology, clinical features, biological mechanism and management of these adverse reactions have been discussed in detail. Although these adverse reactions have been described mainly for substances used illicitly for recreational purposes, several prescription drugs have also been involved; these include mainly psychotropic medications such as opioids, antidepressants, antiepileptics and antipsychotics. These effects can be partly explained by withdrawal syndromes (defined also as 'neonatal abstinence syndrome') caused by the delivery-related discontinuation of the drug disposition from the mother to the fetus, with symptoms that may include feeding disorders, tremors, irritability, hypotonia/hypertonia, vomiting and persistent crying, occurring a few hours to 1 month after delivery. Otherwise, neonatal neurological and behavioral effects can also be caused by a residual pharmacological effect due to an accumulation of the drug in the blood and tissues of the newborn, with various symptoms related to the toxic effects of the specific drug class, usually developing a few hours after birth. With few exceptions, validated protocols for the assessment and management of withdrawal or residual pharmacological effects of these drugs in neonates are often lacking or incomplete. Spontaneous reporting of these adverse reactions seems limited, although it might represent a useful tool for improving our knowledge about drug-induced neonatal syndromes.