Using Cannabis During Pregnancy Linked To Children Born With Aggression And Anxiety, Study Finds

by : Poppy Bilderbeck on : 16 Nov 2021 18:31
Link Between Cannabis and Pregnancy to Child Anxiety and Aggression - Alamy Alamy

A study has revealed that people who smoke cannabis during their pregnancy are more likely to have children who suffer from anxiety and exhibit aggressive behaviour. 

Looking at 322 pairs of mother and children in New York, US researchers conducted the study as part of a wider research project to do with stress during pregnancy.


Marijuana use during pregnancy were linked to the child possibly having higher levels of anxiety, aggression, hyperactivity and even autism and childhood psychosis.

Smoking Weed When Pregnant Links to Anxiety and Aggression in Children - Alamy Alamy

Hair samples were taken from children when they were between three and six years old, to determine their hormone levels, CNN reports.

Heart function was measured via electrocardiogram recordings and parental surveys helped monitor the children’s behaviour and emotions.


Some participants also had their placental tissue collected after they had given birth.

Dr. Daghni, consultant obstetrician and spokesperson for the Royal College of Obstetricians and Gynaecologists in the UK, told Science Media Centre:

This new study supports a growing body of evidence that smoking cannabis during pregnancy is associated with adverse outcomes for women and their children.

We know from previous studies that using cannabis during pregnancy is linked to impaired foetal brain development, stillbirth, low birth weight, and pre-term birth.

This new evidence adds to these existing safety concerns, suggesting that cannabis use in pregnancy could lead to higher anxiety, aggression, hyperactivity, and levels of the stress hormone cortisol in the children.

Pregnant woman (Alamy)Alamy

However, Dr. Daghni noted that only a ‘small sample of women and children’ took part in the study, and that the team would ‘like to see more research done in this area’.

The negative effects on children’s mental wellbeing, from anxiety to aggression, was discovered through analysis of the placental tissue.

Using sequencing RNA, which are molecules similar to DNA that  are part of the genetic code, cannabis use while pregnant was shown as linking to a lower expression of immune-activating genes such as cytokines, which help protect against pathogens.

Dr Darine El-Chaâr, maternal foetal medicine specialist and clinical investigator at Ottawa Hospital Research Institute in Canada, commented on how ‘interesting’ it was to make such links via such a ‘well-designed study, with good methodology, and laboratory design’.

Smoking Weed When Pregnant Links to Anxiety and Aggression in Children - AlamyAlamy

The authors concluded that the results suggested that the risk of mental health problems in early childhood were possibly increased by cannabis use during one’s pregnancy.

While cannabis is often associated with easing stress, ‘in utero expose to cannabis has the opposite effect on children’, said Yoko Nomura, professor of psychology at The City University of New York’s Queens College and Graduate Center.

However, placental gene expression was reviewed as not being able to show on its own the complete impact that cannabis could have on a child if used throughout a pregnancy.


The baby’s sex, ethnicity, age and their parents’ age, marital status and education were all also considered.

Smoking Weed When Pregnant Links to Anxiety and Aggression in Children - AlamyAlamy

Although some of the accuracy of the information was unable to be fully determined. Such as the actual use of cannabis by the women involved, information of which they supplied themselves.

Furthermore, participants’ history of cannabis use, such as prenatal or postnatal cannabis use, was unable to be examined separately by researchers.

The author of the study Yasmin Hurd, the War-Coleman Chair of Translational Neuroscience and the Director of the Addiction Institute at Mount Sinai, said:

Also, we cannot control for various confounds (e.g., lifestyle, parenting, genetics, etc) and would need a study of thousands of individuals to determine the relevance of various factors to the outcome measures.

Hurd warned that while the drug is considered to be ‘safe’, the study emphasised how it can have ‘negative long-term outcomes on children’ and that women should find alternate ways to ‘potentially alleviate morning sickness or anxiety while pregnant’ by talking to doctors.

The study, called Associations Between Prenatal Cannabis Exposure and Childhood Outcomes was published in JAMA Psychiatry

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Topics: Science, Anxiety, Cannabis, pregnancy


CNN and 1 other
  1. CNN

    Using cannabis in pregnancy linked to aggression and anxiety in children, a study suggests

  2. JAMA Psychiatry

    Associations Between Prenatal Cannabis Exposure and Childhood Outcomes Results From the ABCD Study