The prenatal use of opioids, including heroin and opioids prescribed for pain management, can produce a withdrawal condition in newborns known as Neonatal abstinence syndrome (NAS). These and other substances pass through the placenta that connects the baby to its mother in the womb. The baby becomes addicted along with the mother. A recent study found that cases of NAS have tripled over the last decade and that treatment costs for newborns with NAS—most of which are paid by Medicaid—are more than five times the cost of treating other newborns at birth. This book examines federally funded research, federal programs, and other federal agency efforts related to prenatal opioid use or NAS; gaps identified by federal agency officials and experts in efforts to address prenatal opioid use or NAS; and how federal efforts to address prenatal opioid use or NAS are planned and coordinated. It also discusses symptoms and characteristics of NAS.