In this study, we examine the causal link between preprint platforms and research impacts by examining a large sample of 5,434 published articles with preprints deposited on bioRxiv in 2018. We use a text-mining algorithm to match the treated sample to a control group of 8,019 similar articles without depositing preprints. By modeling the differences in citations in subsequent years between the treated and control groups, we establish a positive causal effect of self-archiving platforms on forward citations.