Accumulating evidence from both human and preclinical studies indicates maternal substance use during pregnancy can affect fetal development, birth weight and infant outcomes. Thus, the prenatal period can be regarded as an important and potentially sensitive period of development. In this manuscript, an updated overview of studies on prenatal cannabis exposure in humans is presented, including recent studies conducted within the Generation R study. Findings on fetal growth, birth outcomes, early neonatal behavior and infant behavior and cognitive development are discussed in detail. Preclinical evidence and potential mechanisms are described as well, and recommendations for future studies are provided. It is concluded that evidence seems to suggest that fetal development is affected by prenatal maternal cannabis use, while findings on effects on infant behavior or cognition are inconsistent. Beyond infancy, subtle differences may be found in specific cognitive or behavioral outcomes, although replication studies in which pregnant women and their fetuses are exposed to current and probably higher levels of Δ9-tetrahydrocannabinol and novel designs are needed to come to firm conclusions.