A baby who was exposed to heroin in his or her mother’s womb can be born physically addicted to the drug.
“This is not only true for a woman who has used heroin during pregnancy, but it could also apply to any opiate drug, such as a mother who has been taking methadone (a synthetic opiate used to withdraw from heroin) or prescription opiates,” said Barry Lester, a national expert on prenatal drug exposure and a professor of psychiatry and pediatrics at the Brown University Alpert Medical School in Providence, Rhode Island.
When a pregnant woman takes opiates, the developing embryo is regularly exposed to the drug, Lester said. But once born, the baby is cut off from a drug supply it has become dependent on, and goes through withdrawal.
Known as neonatal abstinence syndrome (NAS), its symptoms — such as excessive crying, slow weight gain, fever, irritability and vomiting — usually take about 72 hours to appear in the newborn.
“Hospital nurseries are seeing a major uptick of babies born with neonatal abstinence syndrome,” Lester told Live Science. He said this is due to the growing number of women who are abusing prescription opioids.
Although the majority of babies born to women who abuse opiates during pregnancy are born addicted to these drugs, studies have found that about 25 to 30 percent of these babies never develop NAS symptoms, Lester said.
Researchers are trying to understand why this happens, and Lester said they suspect there is something fundamentally different about these babies, both genetically and in the makeup of their brains, that may protect them.
Babies who develop NAS need treatment. They are put back on opiates, either morphine or methadone, and these drugs are gradually withdrawn over time until the newborn no longer has symptoms, Lester said.
He said it’s unclear whether babies born with NAS have any long-term effects from this early opiate exposure because the studies done so far have shown inconsistent results.