Prenatal cannabis use may be linked with psychopathology in middle childhood

By Melanie Hinze
New research suggests that prenatal exposure to cannabis increases children’s risk of psychopathology during middle childhood.

Published in JAMA Psychia­try, the cross-sectional study included data for 11,489 children aged 9 to 11 years (mean age 9.9 years) who were recruited from 22 sites across the US between June 2016 and October 2018.

Of these children, 655 (5.7%) were exposed to cannabis prenatally – either only before maternal knowledge of pregnancy (3.6%), or after knowledge of pregnancy (2.1%, with or without exposure before knowledge).

When compared with no cannabis exposure, exposure before or after maternal knowledge of pregnancy was associated with higher psychotic-like experiences, body mass index, and internalising, externalising, attention, thought, social and sleep problems. This was in addition to lower cognition and grey matter volume. Exposure only after maternal knowledge of pregnancy was also associated with lower birthweight, total intracranial volume and white matter volume.

When potential confounders were accounted for, exposure after maternal knowledge of pregnancy remained associated with greater psychotic-like experiences and externalising, attention, thought and social problems.

Professor Claire Roberts, NHMRC Leadership Fellow, Matthew Flinders Professor, and Head of the Pregnancy Health and Beyond Laboratory (PHaB Lab) at Flinders University, Adelaide, said mounting evidence showed that cannabis use in pregnancy was not safe.

‘We and others have shown adverse effects of cannabis use in pregnancy on the baby including increased risk for preterm birth and reduced birthweight, birth length and head circumference, as well as being more than twice as likely to have severe morbidity or die,’ she said.

‘This research shows that the impacts of cannabis use in pregnancy continue into childhood with greater risk for psychopathology, and reduced cognition and grey matter volume in the brain at age 10 years.’

She told Medicine Today that this was a strong signal of the importance of educating young women on the need to discontinue using cannabis. ‘Just because cannabis is being legalised in many places does not mean it is safe,’ she said. ‘The research shows that even stopping once a woman knows she is pregnant will improve outcomes for her child, although of course the brain starts to develop even before that time, so ideally women should stop using cannabis when planning pregnancy.’
JAMA Psychiatry 2020; doi: 10.1001/jamapsychiatry.2020.2902.