‘Striking’: Teens who frequently use cannabis six times more likely to have premature baby

Boys and girls aged 15 to 17 years who used cannabis frequently were six times more likely to have a preterm baby later in life, even if the substance was used prior to conception, a 20-year population cohort study showed.

The National Institute on Drug Abuse lists cannabis as the third “most commonly abused drug” by teenagers. This is the first study to link downstream effects of frequent adolescent cannabis use on the user’s descendants, according to a press release.

“The causes of poor birth outcomes remain unknown in the great majority of cases, though a number of sociodemographic, behavioral and medical risk factors have been identified,” Lindsey Hines, PhD, a research fellow at the University of Bristol in the United Kingdom, and colleagues, wrote in Scientific Reports. “Some of the most clearly documented risks are around maternal substance use.”

The researchers analyzed data regarding tobacco and cannabis use among a group of Australian adolescent boys and girls. The participants were in grade nine at baseline. They were interviewed five more times in 6-month intervals during adolescence (mean age during waves 2 through 6, 15.4-17.4 years) and three times in early adulthood (mean age at wave 7, 20.7 years; mean age at wave 8, 24.1 years; mean age at wave 9, 29.1 years). The final analysis included 665 male and females and 1,030 offspring.

Hines and colleagues reported finding “striking associations.” After adjusting for a broad range of confounders, daily cannabis use while aged 15 to 17 years was associated with sixfold increases in the odds of preterm birth (adjusted OR = 6.65; 95% CI, 1.92-23.09) and low birth weight among offspring (aOR = 5.84; 95% CI, 1.7-20.08), regardless of the parent’s sex.

In addition, adjusted linear models showed that study participants who reported daily cannabis use when aged 15 to 17 years had offspring born on average more than 1 week earlier compared with those whose parents reported no cannabis use (mean difference = 1.49 weeks; 95% CI –3 to 0.03). Parental daily cannabis use as an adolescent was also tied to an average reduction in birth weight by 400 g (mean difference = 0.4 kg; 95% CI, –0.85 to 0.06).

According to the researchers, there was weak evidence that parental daily tobacco use when aged 20 to 24 years was associated with an increase in offspring birth weight (mean difference = 0.14 kg; 95% CI, 0.01-0.27). There was also little evidence of a link between preconception parental tobacco use at other ages or parental tobacco use prior to conceptions. .

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

George Patton, PhD, study co-author and professorial fellow in adolescent health research with the University of Melbourne and Murdoch Children's Research Institute, encouraged “bigger and better research” that looks into the dangers of heavy cannabis use among teenagers.

References:

Hines LA, et al. Sci Rep. 2021;doi.10.1038/s41598-021-95460-2.

National Institute on Drug Abuse. What drugs are most frequently used by adolescents?  https://www.drugabuse.gov/publications/principles-adolescent-substance-use-disorder-treatment-research-based-guide/frequently-asked-questions/what-drugs-are-most-frequently-used-by-adolescents. Accessed Aug. 24, 2021.

University of Bristol. Teens who use cannabis frequently more likely to have premature baby, study suggests. http://www.bristol.ac.uk/news/2021/august/teens-cannabis.html. Accessed Aug. 24, 2021.