The tetrahydrocannabinol (THC) present in cannabis targets the receptors and signalling systems in the brain. For the brain to develop normally, this signalling process should occur unhindered, researchers noted.
During pregnancy, TCH passes from the woman's bloodstream to her baby through the placenta. Cannabis is not known to cause birth defects, but there are now concerns that it may affect the baby's brain and nervous system development.
Research studies indicate that unborn babies exposed to cannabis may be more likely to exhibit behavioural changes as older children. These children may be more impulsive, hyperactive and have attention difficulties, affecting their learning ability. Some studies have found that babies born to women who used marijuana regularly during pregnancy tend to be lighter in weight, shorter in length and have a smaller head circumference at birth.
Previous research has claimed that babies born to mothers who took cannabis while they were pregnant went on to experience problems with physical activity, BBC reports. Cannabis is the most commonly reported illicit drug of choice among young people and the most commonly used illicit drug by pregnant women.
Previous studies, which have investigated the effects of cannabis upon unborn children however, are not common. Since experimental administration of drugs to pregnant women is unethical, studies that do exist have been limited to clinical observations, animal testing or epidemiological investigations.
The new research - an experimental study involving mice - is published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS).
