Dr Miriam – Pregnant mums using cannabis cause disturbing behaviour in children

We know smoking cigarettes and drinking alcohol in pregnancy harms the ­unborn baby. It can cause low weight, a failure to thrive and a vulnerability to chest infections and hospital admissions in infancy.

I remember the moment I read the research that pinpointed the harmful effects of alcohol on unborn babies. Up until then, can you believe it, women drank freely.

The science showed within half an hour of drinking a vodka and orange a baby’s chest movements (early breathing) ceased for an hour or more.

Alcohol is potent stuff to an unborn child. And now it appears cannabis is just as harmful. Smoking it in ­pregnancy has, if anything, more serious implications for babies.

The behaviours of nine-year-old children whose mothers were exposed to cannabis during their pregnancies were monitored in the US Adolescent Brain Cognitive Development study.

It found these children were more likely to behave in a disturbed way if their mothers had smoked cannabis while they were carrying them.

The sleep patterns of 11,489 children, among whom 655 had mothers who smoked the drug while pregnant, were also studied.

The results are shocking. Every child who’d been exposed to cannabis while in the womb had abnormal behaviour.

Compared to the other children they were more likely to have disturbed behaviour and problems with attention span, making friends and sleeping. Plus they had poorer academic ability.

The children’s behaviours were worse if women continued to smoke cannabis after discovering they were pregnant, researchers said.

The US Centers for Disease Control and Prevention, the prestigious public health body, warns that smoking ­marijuana during pregnancy could lead to lower birth weight in newborns, adding it “may make it hard for your child to pay attention or to learn”.

And the researchers have called for better education in the US about the risks of using cannabis during pregnancy, adding that it should be “discouraged”.

Summing up the study, researchers said: “Despite increasingly permissive social attitudes and the marked relaxation of legal restrictions on cannabis use [in the US], prenatal cannabis exposure and the correlated risks that it indexes may place offspring at increased risk for psychopathology in middle childhood.”

They added: “Similar to the effective messaging surrounding the adverse consequences of alcohol and tobacco exposure during pregnancy, education regarding the potential harms ­associated with prenatal cannabis use is necessary.

“Currently, pregnant women, and even those contemplating pregnancy, should be discouraged from using any cannabis by health care professionals, dispensaries, and others.

“Women refraining from cannabis use during pregnancy may benefit [their] offspring.”