Cannabis Use in Pregnancy and Neonatal Outcomes: A Systematic Review and Meta-Analysis

The longitudinal assessment of prenatal cannabis use on neonatal outcomes

OBJECTIVE

To investigate the association between prenatal cannabis use and perinatal outcomes using longitudinal data from pregnant individuals.

STUDY DESIGN

This secondary-data analysis study utilized data collected from 894 pregnant individuals followed in the Stress in Pregnancy longitudinal study, conducted between 2009 and 2013. The status of cannabis use was ascertained through interviews and electronic medical record reviews to evaluate the effect of cannabis use on perinatal outcomes (NICU admission, preterm delivery, low birth weight, fetal death).

RESULTS

Among participants analyzed, 13.1% used cannabis, who were generally younger (25.9 vs 27.9 years). There was a sevenfold increased risk of fetal death (OR 7.30) among cannabis users relative to non-users. Elevated risk persisted after adjustments of potential confounders (aOR 6.31). Adjusted models also suggested increased low birth weight risk (aOR 1.67).

CONCLUSION

This study highlights an association between prenatal cannabis use and elevated risks for fetal death and low birth weight.

Cannabis Science and Therapeutics: An Overview for Clinicians

Cannabis-based therapeutics have garnered increasing attention in recent years as patients seek alternative treatments for various medical conditions. This narrative review provides a comprehensive overview of the science behind the medical use of cannabis, focusing on the medical evidence for commonly treated conditions. In addition, the review addresses the practical considerations of using cannabis as a therapeutic agent, offering insights into dosing strategies, variations in cannabinoid formulation, and individual patient responses. Precautions, adverse consequences, and drug interactions are also discussed, with a focus on patient safety and the potential risks associated with cannabis use.

Risk of Adverse Neonatal Outcomes After Combined Prenatal Cannabis and Nicotine Exposure

Importance

The prevalence of cannabis use in pregnancy is rising and is associated with adverse perinatal outcomes. In parallel, combined prenatal use of cannabis and nicotine is also increasing, but little is known about the combined impact of both substances on pregnancy and offspring outcomes compared with each substance alone.

Objective

To assess the perinatal outcomes associated with combined cannabis and nicotine exposure compared with each substance alone during pregnancy.

Design, Setting, and Participants

This retrospective population-based cohort study included linked hospital discharge data (obtained from the California Department of Health Care Access and Information) and vital statistics (obtained from the California Department of Public Health) from January 1, 2012, through December 31, 2019. Pregnant individuals with singleton gestations and gestational ages of 23 to 42 weeks were included. Data were analyzed from October 14, 2023, to March 4, 2024.

Exposures

Cannabis-related diagnosis and prenatal nicotine product use were captured using codes from International Classification of Diseases, Ninth Revision, Clinical Modification, and International Statistical Classification of Diseases, Tenth Revision, Clinical Modification.

Main Outcome and Measures

The main outcomes were infant and neonatal death, infants small for gestational age, and preterm delivery. Results were analyzed by multivariable Poisson regression models.

Results

A total of 3 129 259 pregnant individuals were included (mean [SD] maternal age 29.3 [6.0] years), of whom 23 007 (0.7%) had a cannabis-related diagnosis, 56 811 (1.8%) had a nicotine-use diagnosis, and 10 312 (0.3%) had both in pregnancy. Compared with nonusers, those with cannabis or nicotine use diagnoses alone had increased rates of infant (0.7% for both) and neonatal (0.3% for both) death, small for gestational age (14.3% and 13.7%, respectively), and preterm delivery (<37 weeks) (12.2% and 12.0%, respectively). Moreover, risks in those with both cannabis and nicotine use were higher for infant death (1.2%; adjusted risk ratio [ARR], 2.18 [95% CI, 1.82-2.62]), neonatal death (0.6%; ARR, 1.76 [95% CI, 1.36-2.28]), small for gestational age (18.0%; ARR, 1.94 [95% CI, 1.86-2.02]), and preterm delivery (17.5%; ARR, 1.83 [95% CI, 1.75-1.91]).

Conclusions and Relevance

These findings suggest that co-occurring maternal use of cannabis and nicotine products in pregnancy is associated with an increased risk of infant and neonatal death and maternal and neonatal morbidity compared with use of either substance alone. Given the increasing prevalence of combined cannabis and nicotine use in pregnancy, these findings can help guide health care practitioners with preconception and prenatal counseling, especially regarding the benefits of cessation.

Influence of substance use on male reproductive health and offspring outcomes

The prevalence of substance use globally is rising and is highest among men of reproductive age. In Africa, and South and Central America, cannabis use disorder is most prevalent and in Eastern and South-Eastern Europe, Central America, Canada and the USA, opioid use disorder predominates. Substance use might be contributing to the ongoing global decline in male fertility, and emerging evidence has linked paternal substance use with short-term and long-term adverse effects on offspring development and outcomes. This trend is concerning given that substance use is increasing, including during the COVID-19 pandemic. Preclinical studies have shown that male preconception substance use can influence offspring brain development and neurobehaviour through epigenetic mechanisms. Additionally, human studies investigating paternal health behaviours during the prenatal period suggest that paternal tobacco, opioid, cannabis and alcohol use is associated with reduced offspring mental health, in particular hyperactivity and attention-deficit hyperactivity disorder. The potential effects of paternal substance use are areas in which to focus public health efforts and health-care provider counselling of couples or individuals interested in conceiving.

Prenatal delta-9-tetrahydrocannabinol exposure alters fetal neurodevelopment in rhesus macaques

Prenatal cannabis use is associated with adverse offspring neurodevelopmental outcomes, however the underlying mechanisms are relatively unknown. We sought to determine the impact of chronic delta-9-tetrahydrocannabinol (THC) exposure on fetal neurodevelopment in a rhesus macaque model using advanced imaging combined with molecular and tissue studies. Animals were divided into two groups, control (n = 5) and THC-exposed (n = 5), which received a daily THC edible pre-conception and throughout pregnancy. Fetal T2-weighted MRI was performed at gestational days 85 (G85), G110, G135 and G155 to assess volumetric brain development. At G155, animals underwent cesarean delivery with collection of fetal cerebrospinal fluid (CSF) for microRNA (miRNA) studies and fetal tissue for histologic analysis. THC exposure was associated with significant age by sex interactions in brain growth, and differences in fetal brain histology suggestive of brain dysregulation. Two extracellular vesicle associated-miRNAs were identified in THC-exposed fetal CSF; pathway analysis suggests that these miRNAs are associated with dysregulated axonal guidance and netrin signaling. This data is indicative of subtle molecular changes consistent with the observed histological data, suggesting a potential role for fetal miRNA regulation by THC. Further studies are needed to determine whether these adverse findings correlate with long-term offspring neurodevelopmental health.

Neonatal outcomes associated with in utero cannabis exposure: a population-based retrospective cohort study

BACKGROUND

The full spectrum of associations between in utero cannabis exposure and adverse neonatal outcomes is still unclear.

OBJECTIVE

This study aimed to evaluate the associations between in utero cannabis exposure and neonatal outcomes.

STUDY DESIGN

This population-based retrospective cohort study of singleton births among Kaiser Permanente Northern California members (January 1, 2011-July 31, 2020) included parent-infant dyads in which the pregnant parent was screened for cannabis use as part of standard prenatal care, generally upon entrance into care. Data were ascertained from electronic health records. Generalized estimating equation models were adjusted for sociodemographic characteristics, other non-cannabis prenatal substance use, medical and mental health comorbidities, and adequacy of prenatal care. In utero cannabis exposure was defined as self-reported use since becoming pregnant and/or a positive urine toxicology test for cannabis at any time during pregnancy (yes/no; primary exposure). Frequency of use was self-reported and categorized as daily, weekly, monthly or less, never, or unknown (secondary exposure). Neonatal outcomes included low birthweight, small for gestational age, preterm birth, neonatal intensive care unit admission, and infant respiratory support.

RESULTS

Of 364,924 infants, 22,624 (6.2%) were exposed to cannabis in utero. After adjustment for potential confounders, including in utero exposure to other substances, in utero exposure to cannabis was associated with greater odds of low birthweight (adjusted odds ratio, 1.20; 95% confidence interval, 1.12-1.28), small for gestational age (adjusted odds ratio, 1.24; 95% confidence interval, 1.18-1.30), preterm birth (<37 weeks; adjusted odds ratio, 1.06; 95% confidence interval, 1.00-1.13), and neonatal intensive care unit admission (adjusted odds ratio, 1.06; 95% confidence interval, 1.01-1.11). There was a suggestive association with early preterm birth (<34 weeks; adjusted odds ratio, 1.11; 95% confidence interval, 1.00-1.23; P=.055), but no significant association with respiratory support (adjusted odds ratio, 1.07; 95% confidence interval, 0.97-1.18). Dose-response analysis found an increasing likelihood of low birthweight and small for gestational age with increasing frequency of prenatal cannabis use by the pregnant individual. Sensitivity analyses further supported an increased likelihood of low birthweight and small for gestational age, although associations with other outcomes did not reach statistical significance.

CONCLUSION

In utero cannabis exposure was associated with increased likelihood of low birthweight, small for gestational age, preterm birth, and neonatal intensive care unit admission. Clinicians should counsel individuals who are pregnant or considering pregnancy about the potential adverse neonatal health outcomes associated with prenatal cannabis use.

Prenatal delta-9-tetrahydrocannabinol exposure is associated with changes in rhesus macaque DNA methylation enriched for autism genes

BACKGROUND

With the growing availability of cannabis and the popularization of additional routes of cannabis use beyond smoking, including edibles, the prevalence of cannabis use in pregnancy is rapidly increasing. However, the potential effects of prenatal cannabis use on fetal developmental programming remain unknown.

RESULTS

We designed this study to determine whether the use of edible cannabis during pregnancy is deleterious to the fetal and placental epigenome. Pregnant rhesus macaques consumed a daily edible containing either delta-9-tetrahydrocannabinol (THC) (2.5 mg/7 kg/day) or placebo. DNA methylation was measured in 5 tissues collected at cesarean delivery (placenta, lung, cerebellum, prefrontal cortex, and right ventricle of the heart) using the Illumina MethylationEPIC platform and filtering for probes previously validated in rhesus macaque. In utero exposure to THC was associated with differential methylation at 581 CpGs, with 573 (98%) identified in placenta. Loci differentially methylated with THC were enriched for candidate autism spectrum disorder (ASD) genes from the Simons Foundation Autism Research Initiative (SFARI) database in all tissues. The placenta demonstrated greatest SFARI gene enrichment, including genes differentially methylated in placentas from a prospective ASD study.

CONCLUSIONS

Overall, our findings reveal that prenatal THC exposure alters placental and fetal DNA methylation at genes involved in neurobehavioral development that may influence longer-term offspring outcomes. The data from this study add to the limited existing literature to help guide patient counseling and public health polices focused on prenatal cannabis use in the future.