New Research on Marijuana Use During Pregnancy: Gene Changes and Essential Insights for Expecting Mothers

With marijuana legalization spreading globally, its use has risen, including among pregnant women. Many view marijuana as a natural remedy for pregnancy symptoms like nausea and anxiety. However, a new study led by Amy Osborne of the University of Canterbury, suggests potential dangers, revealing that prenatal marijuana exposure can cause permanent changes to a child’s DNA. These changes, tied to a process called DNA methylation, can affect biological functions and have long-lasting implications throughout life.

Published in Nature, a leading scientific journal, the research follows the effects of marijuana exposure during pregnancy on DNA methylation from birth through adulthood, indicating that the impacts of marijuana may persist for decades.

What We Know About Marijuana and Pregnancy

If you are pregnant or considering starting a family, you’ve likely been counseled by friends, family, and doctors on how to maintain your health during pregnancy. Where does marijuana fit into the list of pregnancy dos and don’ts? While alcohol is a well-known substance to avoid during pregnancy, marijuana represents a gray area.

A study by Bayrampour et al. (2019) found that women often do not receive adequate counseling from healthcare providers regarding marijuana use during pregnancy. Although marijuana may seem less dangerous than alcohol, it can cross the placenta during pregnancy, entering the fetus’s bloodstream and affecting development. It can also be found in breast milk, meaning the exposure continues even after birth.

For those pregnant or planning to be, understanding the possible consequences of marijuana use is crucial.

Study Findings: Lasting DNA Changes and Implications for Development

Osborne’s study shows that prenatal marijuana exposure is associated with altered DNA methylation in genes related to brain development and cognitive function. These changes were observable at birth and persisted into adolescence and adulthood.

• Gene Activity Alteration: Specific genes like NT5E, LZTS2, and DOCK8, which are essential for neuronal development and neurotransmission, were affected. These changes could potentially impact brain structure or function, leading to cognitive or emotional issues later in life.
• Neurodevelopmental Risks: The methylation changes were still present in individuals as old as 27, highlighting marijuana’s long-term impact. This suggests prenatal marijuana use could predispose children to neurodevelopmental issues such as learning disabilities or mental health conditions like depression, anxiety, and schizophrenia.
• Compounding Risks with Tobacco Use: The study also found that using marijuana alongside tobacco heightened the methylation effects, suggesting that co-exposure could increase the developmental risks for the child.

How Common is Marijuana Use During Pregnancy?

Studies suggest that marijuana is one of the most commonly used substances during pregnancy, with 2-5% of pregnant women reporting marijuana use (Committee on Obstetric Practice, Obstet Gynecol, 2017). The use of marijuana among pregnant women has been rising over time. In 2014, 3.85% of pregnant women reported using marijuana, reflecting a 60% increase from 2002.

Notably, nearly one in five pregnant women who used marijuana met the criteria for cannabis use disorder, meaning their babies were likely exposed to significant levels of the drug (Ko et al., 2015). While rates of alcohol and tobacco use have significantly decreased, marijuana use continues to rise.

Clearly, many pregnant women use marijuana, prompting concerns about its impact on fetal development.

Marijuana’s Effects on Child Health: During Pregnancy and After Birth

During pregnancy, the placenta serves as the lifeline between a mother and her baby, exchanging oxygen and nutrients. Marijuana can cross the placenta, entering the baby’s bloodstream during pregnancy. Research indicates that babies exposed to marijuana in the womb have altered developmental patterns. Studies show these infants are more likely to have low birth weights, which increases their chances of developing future health issues like diabetes and heart disease.

Babies exposed to marijuana are also more likely to require neonatal intensive care (NICU) after birth, further indicating a higher risk of pregnancy complications. Studies using animal models have shown similar effects, where high doses of marijuana during pregnancy resulted in growth retardation and malformations.

Marijuana exposure doesn’t end at delivery. Cannabinoids can be present in breast milk, allowing marijuana to continue affecting babies post-birth. Although research in this area is limited, studies suggest that long-term marijuana users have approximately 20% lower levels of prolactin, a hormone that helps women produce breast milk (Ranganathan, Psychopharmacology, 2008). This reduction may interfere with breastfeeding, affecting the baby’s nutrition.

Additionally, research indicates that men trying to start families should also be cautious of marijuana use. It can disrupt sperm production, hormonal pathways, and fertility.

Mental Health and Behavioral Implications

Osborne’s new study raises concerns about the potential for marijuana exposure in the womb to increase the risk of neuropsychiatric disorders. The genes affected by DNA methylation in this research have been linked to conditions like autism, ADHD, and schizophrenia. These long-term changes may affect children’s behavior and social development.

An Underestimated Risk

Many pregnant women view marijuana as a safer alternative to other substances, partly due to insufficient counseling from healthcare providers. However, even infrequent marijuana use during pregnancy could result in developmental changes that last a lifetime. This study adds to growing evidence that prenatal marijuana exposure can alter a child’s DNA in ways that may affect them for decades.

The Importance of Awareness

As marijuana becomes more widely legalized, public perception of its risks during pregnancy has not kept pace with research findings. Osborne’s new research underscores the need for caution, highlighting the long-lasting impacts that prenatal marijuana exposure can have on a child’s development. Expectant mothers should be fully informed of the potential risks, making informed decisions to protect the long-term health and well-being of their children.