Maternal Cannabis Use Tied To Increased Risk Of Child Behavioral Disorders

A recent study in Psychiatry Research has shed light on the impact of maternal cannabis use disorder (CUD) during and after pregnancy on children’s behavior.

While cannabis use has become widespread, especially after legalization in various U.S. states, research on its long-term effects on children, particularly regarding behavioral disorders, remains limited.

Disruptive behavior disorders (DBDs), such as conduct disorders (CDs) and oppositional defiant disorders (ODDs), are common psychiatric conditions in children. Children with ODD often experience intense anger and resentment, while those with CD tend to show more physical aggression. The rates of DBDs have risen in recent decades, with males being 2.5 times more likely to develop these disorders than females. At the same time, maternal cannabis use disorder has also increased over the past 20 years, particularly among pregnant women, with prevalence rising from 1.01% to 9.8%.

The study analyzed data from over 222,600 mother-child pairs in New South Wales, Australia, collected from January 2003 to December 2005. The mothers were diagnosed with CUD either during pregnancy or postpartum, and a control group of mothers without CUD was also included. The children were monitored from birth until the age of 15, with diagnoses of DBDs made based on hospital records and outpatient visits. The diagnoses followed the International Statistical Classification of Diseases and Related Health Problems, 10th Revision, Australian Modification (ICD-10-AM).

Out of the children studied, 1,003 were diagnosed with DBDs, with 70% being male. Among these, 3.4% were born to mothers diagnosed with CUD during pregnancy, compared to 0.8% whose mothers were diagnosed postpartum. Additionally, 4% of children with DBDs were born to mothers with CUD in both the prenatal and postnatal periods.

Other risk factors were also considered. About 30% of children diagnosed with DBDs came from low socioeconomic backgrounds, and 31% were exposed to maternal smoking during pregnancy. Some children were born pre-term (9.7%) or had low birth weight (6.9%). A small percentage had mothers with depression (2.4%) or who used tobacco during pregnancy (0.5%).

After accounting for these factors, the study found that children exposed to chronic cannabis use during pregnancy had a 3.6 times higher risk of developing DBDs. Other maternal substance use, such as opioid use disorder, also increased the risk of DBDs in children, with a 2.96-fold greater chance of these children being diagnosed with behavioral issues.

The study suggests that cannabis exposure, particularly through the chemical Δ9-tetrahydrocannabinol (THC) in blood and breast milk, may alter brain development by affecting genes involved in neurotransmitter release, increasing the likelihood of behavioral disorders in children.

The findings indicate that maternal cannabis use during pregnancy independently increases the risk of disruptive behavior disorders in both male and female children. This increased risk is not influenced by other factors, such as maternal smoking, drinking, low socioeconomic status, or mental health issues.

However, the study has some limitations. It did not account for paternal substance use or mental health histories, which may also affect the risk of DBDs in children. Additionally, genetic factors such as polygenetic risk scores (PRSs) were not considered, which could also contribute to the development of behavioral disorders.

Despite these limitations, the study underscores the need for public health initiatives to reduce the potential negative effects of maternal cannabis use.