Prenatal Opioid Abuse and Infant Health: Effects of Mandatory Access Prescription Drug Monitoring Programs

While prescribed for pain management in the general population, opioid medications are also typically prescribed during pregnancy to treat common conditions such as lower-back, pelvic, and joint pain, and myalgia and migraine. Almost 15% of privately-insured pregnant women have filled an opioid prescription; the rate is even higher (24%) among pregnant Medicaid enrollees. Opioids are known to cross the placenta, and prenatal use has been linked to various complications, most notably Neonatal Opioid Withdrawal Syndrome (NOWS), preterm delivery, low birthweight, and neural tube and congenital heart defects in observational and retrospective studies Opioid use during pregnancy has escalated dramatically over the past two decades, coinciding with the opioid epidemic in the general population. Among pregnant women entering substance abuse treatment facilities, those reporting any opioid abuse increased from 2% to 28% while NOWS cases have increased more than five-fold.

A significant amount of opioids for non-medical use is obtained either directly or indirectly through “doctor shopping”, some of which also sources street supply. The latter refers to patients obtaining (and filling) prescriptions from multiple providers without the prescribers and dispensers being aware of the other prescriptions. To address this issue, many states have implemented prescription drug monitoring programs (PDMP), an electronic database that tracks prescribers and patients. Currently all states except MO have an operational PDMP, though few states have mandatory access provisions that actually require practitioners to access the PDMP prior to prescribing and dispensing a controlled substance. Where voluntary, utilization rates by providers are quite low, on the order of 14-25%. Prior work suggests that mandatory (but not voluntary) PDMP stipulations are effective in reducing opioid abuse in the general population.

In this study, we provide the first evidence on how these policies have impacted pregnant women and their infants. We exploit variation in the timing of mandatory PDMP adoption, conditional on having an operational PDMP, in a difference-in-differences framework to estimate effects on objective measures of Rx drug abuse among pregnant women (opioid-related admissions to substance abuse treatment facilities) and on birth outcomes. Preliminary estimates indicate that mandatory access provisions have significantly reduce opioid abuse among pregnant women, and improved infant health (higher fetal growth by 0.2%; reduced low birthweight and preterm delivery by 1-2%; % is relative to the baseline mean). Effect magnitudes appear small as these are reduced-form intention-to-treat parameters. Under reasonable assumptions, we also derive treatment-on-the-treated effects, in the process providing plausibly causal effects of prenatal opioid abuse on infant health. In ongoing analyses, we attempt to inform whether the improved infant health reflects a reduction in opioid abuse among women of childbearing age in general or also among pregnant women in particular impacted by the policy. Additional analyses explore heterogeneous responses (across insurance status, maternal characteristics, and prenatal physician contact), and potential spillovers of the policy into the prenatal use of other substances such as heroin, cocaine, and marijuana.