How does prenatal cannabis use affect neonatal outcomes?

By Dr. Priyom Bose, Ph.D.Reviewed by Benedette Cuffari, M.Sc.Jun 23 2024

A recent study published in the Journal of Perinatology used longitudinal data from pregnant individuals to assess the relationship between prenatal cannabis use and perinatal outcomes.

Study: The longitudinal assessment of prenatal cannabis use on neonatal outcomes. Image Credit: OMfotovideocontent / Shutterstock.com

Is it safe to use cannabis when pregnant?

In the United States, the use of recreational cannabis has risen following widespread decriminalization and legalization in many states. This is reflected in increasing use among various sub-populations, including pregnant individuals.

In a recent survey, approximately 22% of pregnant women did not consider weekly cannabis use to be risky. In fact, many pregnant women consider cannabis to be useful in reducing nausea without causing any health risks to the offspring.

This perception is not supported by published literature, which has reported the negative association between cannabis use and fetal outcomes. Cannabis use during pregnancy could result in low birth weight in infants and is a well-known predictor of infant mortality and morbidity. Prenatal cannabis use may also lead to developmental delays, intrauterine growth restriction, and neurobehavioral issues.

Nevertheless, there is limited research on the association between prenatal cannabis use and perinatal loss. Preliminary evidence suggests that chronic cannabis use can prevent implantation and placentation development by adversely impacting the endocannabinoid processes.

About the study

Given the crucial role of the endocannabinoid system in fetoplacental development, the current study evaluates the relationship between cannabis use during pregnancy and neonatal outcomes. The current study also provides new insights into data obtained from the Stress in Pregnancy (SIP) longitudinal study.

The impact of cannabis use on several neonatal outcomes, including fetal death, preterm delivery, low birth weight, and neonatal intensive care unit (NICU) admission, was determined.

Data were collected between 2009 and 2017 at two prenatal obstetric clinics in New York. A total of 894 participants were interviewed, and their medical records were reviewed. Exclusion criteria included the presence of maternal or fetal risk factors and plans to relocate out of the area.

In addition to cannabis use, other variables of interest were maternal weight, race, age, education, marital status, nicotine use, and prior spontaneous abortion. Multiple perinatal outcomes were assessed, including preterm delivery, NICU admission, and birth weight at the time of birth. Fetal death was assessed longitudinally through the prenatal period.

Study findings

Cannabis use during pregnancy was associated with an almost two-fold greater risk of low birth weight and more than six-fold higher risk of fetal death.

The findings concerning the adverse relationship between fetal death and cannabis use are consistent with those documented in other studies. Modifiable and non-modifiable covariates were included in the empirical specifications to determine the robustness of these results.

Modifiable covariates included nicotine use and marital status, but non-modifiable covariates included maternal age and race. Despite controlling for these covariates, the risk associated with cannabis use remained elevated.

For successful embryo implantation, tight regulation of the endocannabinoid ligand anandamide (AEA) is important. Altered AEA levels have been associated with ectopic pregnancies, spontaneous abortion, as well as disrupted decidualization, the latter of which can alter embryo and placental development. Thus, the study findings indicate that the endocannabinoid system plays a crucial role in normal gestational development.

In unadjusted models, an increased risk of low birth weight was observed when cannabis use was included with other predictor variables. Contrary to previously reported findings in the literature, alcohol use during pregnancy was not associated with adverse impacts in the current study. However, this could be due to omitted variables, such as different patterns of use.

Conclusions

The study findings highlight a significant relationship between adverse neonatal outcomes, including low birth weight and fetal death, with prenatal cannabis use. In the future, more extensive studies should evaluate substance use during the entirety of the gestational period.

Future studies are also needed to better understand the mechanisms responsible for the increased risk of fetal death and prenatal cannabis use. Due to the widespread use of cannabis, even among pregnant women, it is crucial to educate individuals of childbearing age on the risks associated with cannabis use.

A key limitation of the current study is the characterization of substance use, as it lacks a detailed description of substance mode, duration, exact timing, including gestation, and amount. Toxicology testing was also absent, which made it impossible to verify the substance use history obtained during interviews. The generalizability of the findings could also be restricted, as the sample came exclusively from an urban setting.