OBJECTIVE: To examine the association between adverse childhood experiences and adverse pregnancy outcomes. METHODS: This cohort study included individuals who enrolled in a perinatal collaborative mental health care program (COMPASS [the Collaborative Care Model for Perinatal Depression Support Services]) between 2017 and 2021. Participants completed psychosocial self-assessments, including an adverse childhood experiences screen. The primary exposure was adverse childhood experiences measured by the ACE (adverse childhood experience) score, which was evaluated as a dichotomized variable, with a high ACE score defined as greater than three. Secondary analyses used the ACE score as a continuous variable. Adverse pregnancy outcomes including gestational diabetes, hypertensive disorders of pregnancy, preterm birth, and small-for-gestational-age (SGA) births were abstracted from the electronic health record. Bivariable and multivariable analyses were performed, including mediation analyses. RESULTS: Of the 1,274 women with a completed adverse childhood experiences screen, 904 (71%) reported one or more adverse childhood experiences, and 290 (23%) reported a high ACE score (more than three adverse childhood experiences). Adverse childhood experience scores were not associated with gestational diabetes or SGA births. After controlling for potential confounders, individuals with high ACE score had 1.55-fold (95% CI 1.06–2.26) increased odds of having hypertensive disorders of pregnancy and 2.03-fold (95% CI 1.38–2.99) increased odds of preterm birth. Each point increase in ACE score was not associated with a statistically increased odds of hypertensive disorders of pregnancy (adjusted odds ratio [aOR] 1.07, 95% CI 0.99–1.15); however, each additional point on the adverse childhood experiences screen was associated with increased odds of preterm birth (aOR 1.13, 95% CI 1.05–1.22). Mediation analyses demonstrated tobacco use, chronic medical problems, and obesity each partially mediated the observed association between high ACE scores and hypertensive disorders of pregnancy. Having chronic medical comorbidities partially mediated the observed association between high ACE scores and preterm birth. CONCLUSION: One in four individuals referred to a perinatal mental health program who were pregnant or postpartum had a high ACE score. Having a high ACE score was associated with an increased risk of hypertensive disorders of pregnancy and preterm birth. These results underscore how remote events may reverberate through the life course.