The U.S. Surgeon General recently issued a public warning that “smoking or vaping marijuana is dangerous for pregnant women and their developing babies.” At a news conference, Adams described modern marijuana as, “far more potent than marijuana produced and sold 20 years ago, with levels of T.H.C. increasing to a range of 12 percent to 25 percent from 4 percent back then. No amount of marijuana use during pregnancy or adolescence is safe.”