A recent study led by academics at the University of Bristol in collaboration with the Murdoch Children’s Research Institute in Australia, is the first of its kind to identify the intergenerational risks of cannabis use.

The new research repeatedly assessed 665 participants on their tobacco and cannabis use between the ages of 14 to 29 years, before pregnancy.

Researchers found that teens who frequently smoke cannabis are more likely to have children born prematurely, even when they become parents up to 20 years later.

Maternal cannabis use during pregnancy is already linked to babies being born preterm and having a low birth weight, which raises the risk of health problems.

Substance use in pregnancy tends to be a continuation of use that started before pregnancy, which raises the question around whether the use of substances before pregnancy can contribute to a baby’s early growth.

The researchers found that babies born to parents aged 29 and over, who had used cannabis every day for a period of time between the ages of 15 and 17, were considerably more likely to be born prematurely, or to have a low birth weight. This was compared to babies born to parents who did not use cannabis during their adolescent years.

Dr Lindsay Hines, Research Fellow in Bristol Medical School, said: “Cannabis is the most commonly used illicit drug amongst teenagers. There is already evidence that frequent adolescent cannabis use increases the risks of poor mental health, but our results indicate there may be further effects that individuals may not anticipate.”

George Patton, Professorial Fellow at the University of Melbourne, added: “The more we study heavy cannabis use in teens, the more problematic it looks. Given growing political and industry drivers for legalisation of use, there is a pressing need for bigger and better research into understanding harms arising from heavy adolescent use.”

Given that the study’s participants were both mothers or fathers of the babies and that heavy teenage use is most common in boys, these findings are particularly important for males.

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