ObjectiveThe COVID-19 pandemic prompted healthcare delivery changes, but the associated impacts on substance use disorder treatment outcomes among pregnant and parenting people are unknown. This study aims to (1) describe COVID-19–driven clinical practice changes, (2) evaluate clinic-level visit attendance patterns, and (3) compare patient-level treatment engagement outcomes across 3 COVID-19 pandemic phases in an OBGYN-addiction treatment clinic.MethodsCOVID-19 phases include pre–COVID-19 (August 2019–February 2020), early COVID-19 (March–December 2020), and COVID-19 vaccine (January–July 2021). OBGYN-addiction treatment clinical practice changes were summarized. Clinic-level attended medical provider visits were analyzed. Patient-level treatment engagement outcomes (buprenorphine continuation, visit attendance, and virtual visits) were assessed in a cohort of pregnant and parenting people enrolled in a clinic research registry. Mixed-level logistic regression models determined the relationship between the COVID-19 phases and the patient-level outcomes.ResultsThe study site made several COVID-19–driven clinical practice changes, including implementing a hybrid virtual/in-person system for medical visits. Clinic-level medical provider appointments increased between the first and second COVID-19 phases and remained high in the third phase. Among participants included in patient-level outcome analyses (N = 27), there were no differences in the early COVID-19 phase compared with the pre–COVID-19 phase in buprenorphine continuation, any visits, or medical visits. There was a decrease in all patient-level outcomes in the COVID-19 vaccine phase compared with pre–COVID-19 (P < 0.05). Virtual visits increased between the first 2 phases and remained high during the third.ConclusionWithin our OBGYN-addiction treatment clinic, implementation of tailored, patient-centered treatment strategies supported clinic- and patient-level treatment engagement throughout the pandemic.