Marijuana use during pregnancy ‘affects’ infant’s weight, behaviour

Marijuana use during pregnancy may affect infant’s weight and may influence behavioural problems.

In a recent study, researchers at the University at Buffalo Research Institute on Addictions found that in addition to the documented negative effects of smoking tobacco during pregnancy, marijuana use may also have its consequences, especially when combined with tobacco use.

“Nearly 30 percent of women who smoke cigarettes during pregnancy also report using marijuana,” said Rina Das Eiden, RIA senior research scientist.

“That number is likely to increase with many states moving toward marijuana legalisation, so it’s imperative we know what effects prenatal marijuana use may have on infants.”

The study found that infants who had been exposed to both tobacco and marijuana, especially into the third trimester, were smaller in length, weight and head size, and were more likely to be born earlier, compared to babies who were not exposed to anything.

They also were more likely to be smaller in length and weight compared to babies exposed only to tobacco in the third trimester. The results were stronger for boys compared to girls.

“We also found that lower birth weight and size predicted a baby’s behavior in later infancy,” Eiden said.

“Babies who were smaller were reported by their mothers to be more irritable, more easily frustrated and had greater difficulty calming themselves when frustrated.

“Thus, there was an indirect association between co-exposure to tobacco and marijuana and infant behavior via poor growth at delivery.”