Marijuana use as a teenager linked to pregnancy issues, premature birth years later

BRISTOL, United Kingdom — Frequent cannabis use as a teenager may lead to issues decades later — not as much for the user, but for their children. A new study finds that heavy marijuana use as an adolescent and young adult can raise the risk of premature birth when those users become parents. The children of teen marijuana users are also more likely to have a low birth weight, raising their risk for future health problems.

A team from the University of Bristol studied 665 participants between the ages of 14 and 29 before pregnancy. They also examined their offspring after the group became parents. Study authors note their report is the first to identify a link between frequent cannabis use and generational health risks.

Their findings reveal that parents over 29 who used marijuana heavily between ages 15 and 17 are “considerably more likely” to have either a preterm baby or a child with low birth weight. Researchers note the results apply to both male and female participants.

“Cannabis is the most commonly used illicit drug amongst teenagers. There is already evidence that frequent adolescent cannabis use increases the risks for poor mental health, but our results indicate there may be further effects that individuals may not anticipate,” says Dr. Lindsey Hines in a university release.

“As regulations around legal use liberalize, there is a possibility that adolescent use may increase in some countries. These findings provide additional motivation for ensuring that policy changes do not lead to greater adolescent use.”

It’s never a good time to smoke for parents

Previous studies have discovered that tobacco and marijuana use during pregnancy also contributes to higher rates of preterm births and underweight infants. Since substance use during pregnancy typically starts much earlier than that, the team wanted to look at the effects of marijuana use up to 20 years before a smoker decides to start a family.

Their results show that 20 percent of all premature births among the study group occurred among parents who used cannabis daily as a teen.

“The more we study heavy cannabis use in the teens, the more problematic it looks. Given growing political and industry drivers for legalization of use, there is a pressing need for bigger and better research into understanding harms arising from heavy adolescent use,” adds George Patton, Professorial Fellow in Adolescent Health Research with the University of Melbourne and Murdoch Children’s Research Institute.

The study appears in the journal Scientific Reports.