Several factors have contributed to the increase in cannabis use among expectant mothers in recent years. This chapter summarizes these factors and the potential effects of cannabis on neonates exposed in utero. The literature review focused on 15 clinical (human) studies and 14 preclinical (animal) studies, as shown in the tables below. Clinical studies analyzed three major variables: low birth weight (LBW), preterm birth (PTB), and neonatal intensive care unit (NICU) admission. Animal studies were grouped into LBW, PTB, and other outcomes. Human studies linked prenatal cannabis exposure (PCE) to higher rates of PTB, LBW, and NICU admissions. Although animal models confirmed effects on LBW, findings on PTB were inconsistent. Animal studies also showed that PCE alters neurotransmitter systems, including dopamine, gamma-aminobutyric acid (GABA), and the endocannabinoid system, and impairs executive function. Interestingly, prenatal exposure to cannabidiol, a nonintoxicating cannabis component, was associated with positive effects on neuronal survival. In conclusion, both human and animal studies show consistent effects of PCE on LBW in neonates. However, further controlled animal studies are needed to isolate the effects of cannabis exposure from co-use with other substances, particularly tobacco and nicotine, to better understand cannabis’ specific effects.