The role that stressful life events (SLEs) play in the etiology of teenage pregnancy and adverse birth outcomes, including preterm birth (PTB), has been increasingly acknowledged in the literature. However, studies in this area have revealed inconsistent findings, and existing research syntheses have not examined the temporal relationship between major SLEs (i.e., childhood maltreatment, intimate partner violence [IPV], severe mental illness [SMI], and incarceration), and common negative pregnancy outcomes. To address these limitations, five literature databases (PsycINFO, Web of Science, PubMed, Scopus, and CINAHL) were searched for longitudinal studies examining the impact of the aforementioned SLEs on teenage pregnancy or PTB. We identified 1,540 articles; 46 articles met the inclusion criteria and were included in meta-analyses. Quality assessment of included studies was conducted. Pooled odd ratios (ORs) were calculated using random effects models, and subgroup analyses were performed to investigate the moderating effects of predefined study characteristics on the effect sizes. Statistical analyses were performed in R. Experiencing any of the SLEs explored in this meta-analysis increased the risk of teenage pregnancy (pooled ORs = 1.76; 95% CI [1.56, 1.98]). While there was no significant association between childhood maltreatment and PTB, women who had experienced any form of IPV, been diagnosed with a SMI before or during pregnancy, or been incarcerated during pregnancy, had an elevated risk of having a PTB. The findings of this study emphasize the importance of screening for SLEs across the lifespan and delivering tailored integrated responses to improve birth outcomes.