Among adolescents, cannabis is the third most commonly used illicit drug, behind alcohol and e-cigarettes. The harmful effects of cannabis on the developing brain have long been a concern of many public health experts. Given that frequent marijuana use during the teen years is associated with changes in brain areas involved in attention, memory, decision-making and motivation. Now a new study have taking it further to suggest that Teen who use cannabis frequently, are more likely to have premature babies down the line. Whether it is eaten, drunk, smoked, or vaped, no amount of marijuana use during pregnancy or adolescence is safe.