Cannabis Use During Pregnancy Impacts the Placenta and May Affect Subsequent Child Development

Summary: Mothers who use cannabis during pregnancy to relieve stress may be putting their children at risk of developing anxiety and stress later in life. Researchers found placental tissue revealed cannabis use in mothers was associated with lower expression of immune-activating genes. Cannabis suppression of placental immune-gene networks predicted higher anxiety in children.

Source: Mount Sinai Hospital

Women who use cannabis during pregnancy, potentially to relieve stress and anxiety, may inadvertently predispose their children to stress susceptibility and anxiety, according to a study conducted by researchers from the Icahn School of Medicine at Mount Sinai and the City University of New York.

As legalization of recreational cannabis progresses across the world, many people mistakenly believe that cannabis use is without significant health risks. In line with this softening public opinion, cannabis has emerged as one of the most consumed recreational drugs of abuse during pregnancy, yet the impact of maternal cannabis use on fetal and childhood development is not clear.

“We know that cannabinoid signaling plays a role in modulating stress, which is why some people use cannabis to reduce anxiety and relax,” said Yoko Nomura, Professor of Psychology at CUNY Graduate Center and Queens College and first author of the paper.

“But our study shows that in utero exposure to cannabis has the opposite effect on children, causing them to have increased levels of anxiety, aggression, and hyperactivity compared to other children who were not exposed to cannabis during pregnancy.”

For this study, researchers from Icahn Mount Sinai and CUNY examined placental gene expression and early childhood behavior and physiology in a long-term study of 322 mother-child pairs who were drawn from an ongoing New York City-based study of stress in pregnancy started in 2009.

When the children were approximately six years old, hormone levels were measured via their hair samples, electrocardiogram recordings were used to measure heart function during a stress-inducing condition, and behavioral and emotional functioning was assessed based on surveys administered to the parents.

The children of mothers who used cannabis during pregnancy showed higher anxiety, aggression, hyperactivity, and levels of the stress hormone cortisol, compared to children of non-cannabis users. Maternal cannabis use was also associated with a reduction in the high-frequency component of heart rate variability—the change in time interval between heart beats—which normally reflects increased stress sensitivity.

In addition, RNA sequencing of placental tissue collected at the time of birth in a subset of participants revealed that maternal cannabis use was associated with lower expression of immune-activating genes, including pro-inflammatory cytokines, which are involved in protecting against pathogens.

The cannabis-related suppression of several placental immune-gene networks predicted higher anxiety in the children.

Pregnant women are being bombarded with misinformation that cannabis is of no risk, while the reality is that cannabis is more potent today than it was even a few years ago. Our findings indicate that using it during pregnancy can have long-term impact on children,” said Yasmin Hurd, Ph.D., the Ward-Coleman Chair of Translational Neuroscience, Director of the Addiction Institute at Mount Sinai, and senior author of the paper.

“The study results underscore the need for nonbiased education and outreach to the public and particular vulnerable populations of pregnant women regarding the potential impact of cannabis use. Disseminating this data and accurate information is essential to improving the health of women and their children.”

Abstract

Maternal cannabis use is associated with suppression of immune gene networks in placenta and increased anxiety phenotypes in offspring

While cannabis is among the most used recreational drugs during pregnancy, the impact of maternal cannabis use (mCB) on fetal and child development remains unclear. Here, we assessed the effects of mCB on psychosocial and physiological measures in young children along with the potential relevance of the in utero environment reflected in the placental transcriptome.

Children (∼3 to 6 y) were assessed for hair hormone levels, neurobehavioral traits on the Behavioral Assessment System for Children (BASC-2) survey, and heart rate variability (HRV) at rest and during auditory startle. For a subset of children with behavioral assessments, placental specimens collected at birth were processed for RNA sequencing. Hair hormone analysis revealed increased cortisol levels in mCB children. In addition, mCB was associated with greater anxiety, aggression, and hyperactivity.

Children with mCB also showed a reduction in the high-frequency component of HRV at baseline, reflecting reduced vagal tone. In the placenta, there was reduced expression of many genes involved in immune system function including type I interferon, neutrophil, and cytokine-signaling pathways. Finally, several of these mCB-linked immune genes organized into coexpression networks that correlated with child anxiety and hyperactivity.

Overall, our findings reveal a relationship between mCB and immune response gene networks in the placenta as a potential mediator of risk for anxiety-related problems in early childhood.