Medical Marijuana Legalization in Oklahoma: Effects on Neonatal Exposure to Opiates

The U.S. opioid epidemic has been characterized by increases in opioid misuse, overdose deaths, and neonatal opioid withdrawal syndrome. Research suggests that marijuana legalization has contributed to decreased use of opiates, although many studies had methodological weaknesses and failed to address the pregnant population. Implementation of medical cannabis laws has the potential to reduce maternal opioid use and, therefore, neonatal exposure to the drugs. This study aimed to examine the association between Oklahoma's implementation of state medical marijuana laws and the neonatal exposure to opioids.

Electronic medical records at two sites (Oklahoma City and Lawton) were searched for results of cord, urine, and meconium screens to detect amphetamines, barbiturates, benzodiazepines, cocaine, ethanol, opiates, phencyclidine, and tetrahydrocannabinol (THC). Two study periods were compared: 19 months before Oklahoma's medical marijuana law took effect and 19 months after legalization began.

A total of 16,804 babies were born alive at the two sites during the study period. The rate of positive THC tests per 1,000 liveborn infants significantly increased from 16.2 per 1,000 during the prelaw period to 22.2 per 1,000 during the postlaw period (p = 0.004). Neonatal opioid exposure incidence showed a nonsignificant decrease from 7.6 positive tests per 1,000 liveborn infants to 6.8 per 1,000 from prelaw to postlaw period (p = 0.542). The number of positive tests for THC and concomitant use of opioids doubled from the prelaw period (n = 4) to postlaw (n = 9), but there were too few cases for statistical significance. Infants at the more rural site had significantly higher rates for amphetamines, benzodiazepines, and THC, with a trend toward higher rates for opiates.

Marijuana legalization was related to significant increases in positive test rates for THC, but no significant change/association was noted for neonatal exposure to opioids.

· Prior studies have not examined neonatal exposure to opioids following marijuana legalization.. · Oklahoma's new law led to higher neonatal marijuana exposure.. · Legalization of medical marijuana did not change Oklahoma's neonatal opioid positivity rate..