Marijuana is the most commonly used illegal drug, especially among young women in Western societies. The effects of cannabis use during pregnancy have been studied for many years. The vast majority of studies have shown a link between maternal consumption of cannabis and foetal development. Foetal growth restriction seems to be the major complication of cannabis exposure. Nevertheless, all these studies have suffered from several methodological biases. The maternal marijuana use should be first and foremost detected in pregnant women for a specific addiction management and pregnancy follow-up.