BACKGROUND: No published study to date has reported on the association between preferred language and COVID-19 vaccine uptake during pregnancy, and even less is known about COVID-19 vaccine disparities during lactation. OBJECTIVES: To assess COVID-19 vaccine uptake during pregnancy and lactation by language, English proficiency, and race/ethnicity. STUDY DESIGN: We conducted a retrospective cohort study using electronic health records (EHR) from four US healthcare systems. The study included patients receiving prenatal care who had a live birth between December 2020 September 2022 and no COVID-19 vaccinations before pregnancy (pregnancy analysis) or delivery (lactation analysis). Self-identified (i) preferred language, (ii) limited English proficiency, based on patient request for an interpreter, and (iii) race and ethnicity were identified from EHR. The primary outcome was receipt of the first dose of the COVID-19 vaccine during pregnancy for the pregnancy analysis, and between delivery and human milk feeding discontinuation, up to 180 days after delivery, for the lactation analysis. Adjusted rate ratios (aRR) and 95% confidence intervals (CI) for receipt of first COVID-19 vaccine dose during pregnancy or lactation were estimated separately. RESULTS: Among 10,332 individuals eligible for initial COVID-19 vaccine during pregnancy, groups with lower uptake during pregnancy included Ethiopian languages (aRR 0.60, 95% CI 0.43-0.83) and Somali (aRR 0.39, 95% CI 0.28-0.54) versus English language, limited versus no limited English proficiency (aRR 0.66, 95% CI 0.58-0.76), and non-Hispanic Black versus White (aRR 0.56, 95% CI 0.51-0.62). Among 9271 individuals, groups with lower uptake during lactation included Ethiopian languages (aRR 0.48, 95% CI 0.30-0.77) and Somali (aRR 0.60, 95% CI 0.46-0.80) versus English language, and non-Hispanic Black versus White (aRR 0.77, 95% CI 0.70-0.86). Temporal trends showed lower vaccine uptake for non-English preferred language and non-Hispanic Black groups during pregnancy and lactation, especially during the earlier months of vaccine roll-out. CONCLUSIONS: There were language and racial/ethnic disparities in initial perinatal COVID-19 vaccination. The findings highlight the need to address language-related and other barriers during the rollout of new vaccines.