Doctors have calculated the likelihood of mental retardation and autism in children whose mothers smoked marijuana

There is considerable evidence in the scientific literature that marijuana use during pregnancy harms the fetus and impairs normal growth. Now scientists have discovered how cannabis exposure in utero increases children's risk of autism spectrum disorders (ASD), attention deficit hyperactivity disorder (ADHD) and mental retardation.

A fresh study on the effects of pregnant women smoking cannabis was presented at the April 6-9 congress of the European Psychiatric Association. Within its framework, a team of scientists from Curtin University (Australia) analyzed the data of more than 222 thousand pairs of mothers with children born in the Australian state of New South Wales from January 2003 to December 2005. Their information was compared with information from medical registries containing data on the mothers' prenatal cannabis use and subsequent neuropsychiatric disorders in their babies.

Using statistical analysis, the researchers found that offspring of mothers who smoked marijuana during pregnancy were 98% and 94% more likely to have ADHD and autism spectrum disorders than children who were not exposed to cannabis in utero. The former were also nearly 50% more likely to have intellectual disabilities.

Plus, the doctors found that if, in addition to cannabis, mothers smoked tobacco during pregnancy, the harmful effect was stronger: the already increased risk of ADHD, autism and intellectual disability in children increased even more.

The study also found that babies who were exposed to cannabis in utero were more likely to be born prematurely and have low birth weights, further increasing the likelihood of impaired neuropsychiatric development.

The European Psychiatric Association called the study unique, emphasizing that it provided a more complete picture of the potential risks associated with prenatal cannabis use. Medics expressed concern about the popularity of marijuana among young women in the European Union, including pregnant and lactating women. Doctors called for more education to raise awareness among expectant mothers about the consequences of smoking marijuana during pregnancy.

Psychiatrists are also alarmed by the growing prevalence of ADHD and autism. It is estimated that approximately 5.3 to 5.9 percent of children and adolescents suffer from attention deficit hyperactivity disorder worldwide, and about 4.6 percent in Europe. Autism spectrum disorders occur in about one in two thousand children in the EU.

Earlier, a group of specialists from Canada in a series of experiments with laboratory rats of the Wistar line showed that cannabis use during pregnancy leads to serious cognitive impairment in offspring, which can persist for life.