Birth Outcomes of Neonates Exposed to Marijuana in Utero

This systematic review and meta-analysis compares adverse neonatal outcomes among mothers exposed to marijuana during pregnancy vs mothers not exposed to marijuana during pregnancy in 16 cohort studies.
Key Points Question Are adverse neonatal outcomes associated with exposure to marijuana among mothers during pregnancy? Findings In this meta-analysis of 16 studies including 59 138 patients, maternal marijuana exposure during pregnancy was associated with increased risk of preterm deliveries and neonatal intensive care unit admission and decreased mean birth weight, 1-minute Apgar score, and head circumference of babies. There were no differences in mean 5-minute Apgar score or total infant length. Meaning This study found that women using marijuana during pregnancy may be at increased risk of some adverse neonatal outcomes.
Importance While some studies have found an association between marijuana use and adverse neonatal outcomes, results have not been consistent across all trials. Objective To assess available data on neonatal outcomes in marijuana-exposed pregnancies. Data Sources PubMed, Medline, ClinicalTrials.gov, Cochrane, Scopus, and Web of Science were searched from each database's inception until August 16, 2021. Study Selection All interventional and observational studies that included pregnant women who were exposed to marijuana compared with pregnant women who were not exposed to marijuana and that reported neonatal outcomes were included. Data Extraction and Synthesis Reporting followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses guideline. Data were extracted by 2 authors for all outcomes, which were pooled using a random-effects model as mean difference or risk ratio (RR) and 95% CI. Data were analyzed from August through September 2021. Main Outcomes and Measures All outcomes were formulated prior to data collection. Outcomes included incidence of birth weight less than 2500 g, small for gestational age (defined as less than the fifth percentile fetal weight for gestational age), rate of preterm delivery (defined as before 37 weeks’ gestation), gestational age at time of delivery, birth weight, incidence of neonatal intensive care unit (NICU) admission, Apgar score at 1 minute, Apgar score at 5 minutes, incidence of an Apgar score less than 7 at 5 minutes, fetal head circumference, and fetal length. Results Among 16 studies including 59 138 patients, there were significant increases in 7 adverse neonatal outcomes among women who were exposed to marijuana during pregnancy vs those who were not exposed during pregnancy. These included increased risk of birth weight less than 2500 g (RR, 2.06 [95% CI, 1.25 to 3.42]; P = .005), small for gestational age (RR, 1.61 [95% CI, 1.44 to 1.79]; P