Marijuana Use in Opioid Exposed Pregnancy Increases Risk of Preterm Birth

Document Type


Publication Date



Background: The prevalence of opioid use disorder has increased across the United States, but the rural population of Appalachia has been disproportionately impacted. Concurrently, the slow, but steady progress in the legalization of marijuana may be affecting perception of marijuana use in pregnancy. However, marijuana use in pregnancy has been associated with adverse perinatal outcomes. Concomitant use of opioids and marijuana in pregnancy has not been evaluated. Objective: The primary aim of the study was to evaluate the association between confirmed marijuana use in late pregnancy and preterm birth in opioid-exposed pregnancies. Methodology: A retrospective chart review was conducted that included all births from July 2011 to June 2016 from 6 delivery hospitals in South-Central Appalachia. Out of 18,732 births, 2368 singleton pregnancies indicated opioid use and met remaining inclusion criteria, with 108 of these mothers testing positive for marijuana at delivery. Independent sample t-test and Chi-Square analyses compared marijuana and non-marijuana exposed groups on maternal and neonatal outcomes. Regression analyses controlled for confounding variables in predicting neonatal abstinence syndrome (NAS), NICU admission, preterm birth, small for gestational age, and low birth weight outcomes as shown in Table 1. Results: Neonates born to marijuana-positive women in opioid-exposed pregnancy were more likely to be born preterm, small for gestational age, have low birth weight, and be admitted to NICU. After statistically controlling for parity, marital status, tobacco and benzodiazepine use, preterm birth and low birth weight remained statistically significant with aOR of 2.35 (1.30–4.24) and 2.01 (1.18–3.44), respectively. Conclusions: Maternal use of marijuana in any opioid-exposed pregnancy may increase risk of preterm birth and low-birth weight infants. Prospective studies need to examine the dose and timing of marijuana and opioid use in pregnancy to better delineate perinatal effects. Nonetheless, pregnant women using opioids, including recommended medication assisted treatment for opioid use disorder, should be educated about the risks of concurrent marijuana use during pregnancy and may need to be counseled to abstain from marijuana use during pregnancy for an optimal outcome.