Exposure to cannabis in the womb has surprising effects on development

Infants exposed to marijuana in the womb showed higher language abilities than those who were not exposed to the drug in utero, new research has found. 

Scientists from Illinois and South Dakota were surprised at their findings, which showed children whose mothers smoked marijuana while pregnant had developed language and motor skills that exceeded those of children whose mothers did not use the drug.

Experts caution, however, that the results do not mean expectant mothers should begin consuming weed, as it also has been shown to cause neurodevelopmental issues in infants, as well as low birth weight, similar to the harms associated with drinking while pregnant. 

And while their elevated language and motor skills could mean those children perform better in school than children who were not exposed, further research is needed to study the association. 

The authors of the study, published in the journal Frontier in Pediatrics, said: ‘Exposed infants demonstrated increased expressive and receptive language scores at 12 months of age, which can translate to better performance in school.

‘However, further research is needed to determine the implications of these results later in childhood.’

The 207 mothers included in the study and their babies were assessed at 12 months after the mothers submitted questionnaires about their cannabis use and their child’s development. 

Cannabis use was designated as happening early in pregnancy and in the second or third trimester.

Babies were assessed using the Mullen Scales of Early Learning (MSEL) assessment tool, which evaluates gross motor, fine motor, visual reception, receptive language, and expressive language skills.  

Of the two groups of babies, 69 were exposed to cannabis in the womb, and 138 were unexposed. Children who were exposed early in pregnancy were more likely to have improved gross motor skills.

Based on the findings, researchers concluded that the scores for early-exposed infants could be between 1.75 and 13 points higher than those of unexposed infants.

Meanwhile, the range of scores for receptive language – a child’s ability to understand words, sounds and visuals – were 0.4 to nearly nine points higher in babies exposed to marijuana later in pregnancy than those not.

Late-exposed infants may also have increased scores of expressive language – a child’s skill in using words and forming sentences –  that could be between 2.5 and nearly 13 points higher than unexposed infants.

THC is the psychoactive chemical in cannabis and it can cross the placenta and impact the developing fetus.

A study in the journal Nature Medicine examined data from the birth registry in Ontario, Canada, studying all live births from April 1, 2007, to March 31, 2012. 

It found that for every 1,000 person-years of observation, four cases of autism spectrum disorder were diagnosed among children exposed to cannabis. 

Person-years reflect the total time of observation or follow-up across all subjects included in the study, adjusted for the number of people and the length of time each one was monitored.  

Another study in the journal Canadian Family Physician found babies born to women who used cannabis had ‘withdrawal’-like syndrome as newborns, which was demonstrated by an increase in startles and tremors and reduced ability to adjust to light.

By preschool age, children exposed to cannabis during pregnancy started showing problems with verbal and visual reasoning, hyperactivity, attention deficits, and impulsivity.

These issues were seen in both study groups and continued throughout their school years. At age 10, these children also began to show signs of depression and anxiety.

These emotional symptoms were linked to earlier cannabis use and lower achievements in adolescence and early adulthood.

In some areas of the US up to one-quarter of pregnant women use marijuana during pregnancy, a study in the journal JAMA found.

And in 2022, researchers in Canada found one in 50 pregnant women used cannabis in legalized areas.

The same study found mothers-to-be who used cannabis were 32 percent more likely to be diagnosed with gestational diabetes, and 13 percent more likely to need a C-section, which increases risks for both mother and baby during delivery.

Researchers behind the latest study said: ‘Based on concerns for impaired neurodevelopment, as well as maternal and fetal exposure to smoking, the American College of Obstetricians and Gynecologists (ACOG) recommends avoiding the use of cannabis in women who are pregnant or contemplating pregnancy.’

Their research suggests the stage of pregnancy at which the child is exposed to marijuana matters, possibly affecting brain regions that include cannabinoid receptors. 

Still, they did not offer an explanation as to why the drug may cause this benefit in some of the babies.  

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Marijuana legalization across the US, which has been implemented for recreational use in 24 states, has set off a progressive experiment in the effects of cannabis use on populations young and old, pregnant and not.

US drug officials have recently announced that they would reschedule marijuana to remove it from the Schedule One category, which placed it in the same category as heroin, to schedule three, with the likes of testosterone and ketamine.

The proposal, which will be reviewed by the White House Office of Management and Budget (OMB), would acknowledge that it has less potential for abuse than some of the nation’s most dangerous drugs like heroin and MDMA.

At the same time, the harms of marijuana use are becoming more and more evident. At least 290 American children have suffered brutal, preventable deaths linked to marijuana over the last decade.

The highest proportion of deaths – 95 – involved extreme violence, including the case of a Texan man who murdered his girlfriend and nine-month baby with a pocket knife while suffering what was believed to be a cannabis-induced psychotic episode.

It also appears to be the driving force behind a rise in auto collisions. A DailyMail.com/TIPP survey of 1,435 adults found that 52 percent said cannabis use was driving up the number of vehicle collisions.

Meanwhile, the 12.5 million stoned drivers who got behind the wheel marked a 15 percent rise on the previous year.