Fetal Cannabis Exposure and Neonatal Outcomes: A Systematic Review and Meta-Analysis

Current literature addressing fetal cannabis exposure and neonatal outcomes is based on subjective measures with varying levels of significance. This systematic review and meta-analysis determined if neonates with fetal cannabis exposure have an increased odds of being born small for gestational age, low birth weight, admitted to the Neonatal Intensive Care Unit (NICU) immediately after delivery, and/or preterm.

To identify relevant articles, we searched five databases using standard search criteria. Two authors used the Newcastle-Ottawa Scale to exclude articles with a high risk of bias. To estimate the combined effect, we calculated pooled odd ratios (OR) with 95% confidence intervals (CI) using the Mantel-Haenszel method for dichotomous data.

Of 3,390 original articles we identified through the search strategy, 13 met the inclusion criteria. This meta-analysis indicates that neonates with fetal cannabis exposure have higher odds of being small for gestational age (OR = 1.79; 95% CI = 1.24-2.59) and/or having a low birth weight (OR = 1.38; 95% CI = 1.05-1.89) compared to neonates without fetal cannabis exposure. The results regarding NICU admission and preterm birth were statistically inconclusive (NICU admission: OR = 1.38, 95% CI = 0.86-2.22; Preterm birth: OR = 1.29, 95% CI = 0.97-1.71). Although the odds ratios for these associations span one suggesting a null relationship, they have an upper bound that may be clinically relevant.

Based on these findings, further research, as well as an evaluation of the current public health response, is warranted. Additional research is needed to identify the association between neonatal outcomes and specific nuances of fetal cannabis exposure, such as route of ingestion, frequency of use, dose consumed, and the timing of intrauterine exposure.