Change in marijuana use from adolescence to young adulthood and its relation to gestational alcohol and marijuana exposure.

Prenatal alcohol and marijuana exposure were significantly related to transitions of marijuana use from adolescence to young adulthood, controlling for peers' use, behavior problems, and home environment. While gestational marijuana exposure was associated with early initiation/increasing use, alcohol exposure was related to later initiation. The findings emphasize the long-term effects of prenatal exposure to alcohol and marijuana.