In an effort to identify neonatal complications associated with antenatal opioid analgesic exposure and to establish predictors of neonatal abstinence syndrome (NAS), Vanderbilt University researchers looked at data for mothers and infants enrolled in the Tennessee Medicaid program between 2009–11. The results indicate that of more than 112,000 pregnant women, 28% filled at least one opioid prescription. In addition, women prescribed opioid analgesics were more likely than those not prescribed opioids to have depression, anxiety disorder, and to smoke tobacco. Meanwhile, infants with NAS and those exposed to opioids were more likely to be born at a low birth weight than unexposed infants. Factors associated with increased risk of NAS include higher cumulative opioid exposure for short-acting preparations, opioid type, tobacco use, and selective serotonin reuptake inhibitor use.