Preterm birth research is poised to explore the mental health of adults born very preterm(VP; <32 weeks gestational age) and/or very low birth weight(VLBW; <1500g) through individual participant data meta-analyses, but first the previous evidence needs to be understood. We systematically reviewed and assessed the quality of the evidence from VP/VLBW studies with mental health symptoms or disorders appearing in adulthood, excluding childhood onset disorders. Participants (≥18 years, born >1970) included VP/VLBW individuals with controls born at term(≥37 weeks) or with normal birth weight(NBW; ≥2500g). Thirteen studies were included. Studies consistently showed an increased risk for psychotropic medication use for VP/VLBW adults in comparison to NBW/term controls, but whether VP/VLBW adults have an increased risk for mental health disorders or symptoms appearing in adulthood remains uncertain. The quality of the evidence was moderate (65.8%) to high (34.2%). Further research in larger samples is needed.