In this issue of Epidemiology, Stalberg and colleagues report the lack of an association between prenatal ultrasound and risk of schizophrenia in adulthood. These findings contribute to the search for unintended effects of an intervention designed to improve prenatal care. Although no adverse effect of ultrasound was reported, other gestational exposures have been associated with increased risk of schizophrenia. By extending the causal time frame to include long-term latent effects we are confronted with a potential paradox: interventions beneficial in early life may have undetected adverse consequences in adulthood.