INTRODUCTION: With COVID-19 becoming more endemic, trimester-specific infection risks are important to study. Here, we examine the effect of SARS-CoV-2 positivity by trimester on development of preeclampsia. METHODS: This was an IRB-approved, retrospective cohort study of patients receiving prenatal care and delivering at a single academic hospital from January 1, 2019, to December 30, 2022. Primary outcomes were rate and severity of preeclampsia. Secondary outcomes were characteristics of placental pathology. RESULTS: 6,174 patients met inclusion criteria, 649 of whom were SARS-CoV-2-positive during pregnancy. Of SARS-CoV-2-positive patients, 19.4%, 40.8%, and 39.8% tested positive in the first, second, and third trimesters, respectively. Preeclampsia rates were higher in first (19.2%) and second (18.2%) but not third (11.2%) trimester compared to no infection (11.7%; P=.001). After adjusting for confounding factors, second-trimester SARS-CoV-2-positive patients were 48% more likely to develop preeclampsia than uninfected (95% CI, 1.04–2.11; P=.005). Severity was increased in all trimester infections versus no infection (P=.008), but adjusted analyses showed this difference remained only in first-trimester infections (odds ratio 6.55 [1.90–22.55]; P=.003). SARS-CoV-2 infection in the second trimester was also associated with 63% increase in meconium-stained placenta (95% CI, 1.01–2.61; P=.044), but no other studied placental pathology. CONCLUSION: Consistent with timing of pathogenesis of preeclampsia in late first/early second trimester, patients infected with SARS-CoV-2 in the first and second trimester had higher rates of preeclampsia and severity. This finding helps clarify conflicting studies versus the risk of preeclampsia with SARS-CoV-2 infection in that this risk may be trimester specific and can help aid in our counseling and proposed future research.