Antinuclear antibody positivity is not associated with disease severity in early-onset preeclampsia.

Early-onset preeclampsia (EOPE) is a severe hypertensive disorder of pregnancy that is frequently associated with immune dysregulation. Antinuclear antibodies (ANA) are frequently detected in these patients, but their clinical significance remains unclear. This study aimed to determine the prevalence of ANA positivity and its association with disease severity, as well as maternal and neonatal outcomes, in women with EOPE. This single-center retrospective cohort study included 284 pregnant women diagnosed with EOPE who underwent ANA testing between January 2011 and December 2023. Patients were categorized as ANA-positive (titer ≥ 1:80) or ANA-negative (titer < 1:80). ANA positivity was present in 84 patients (29.6%). Baseline characteristics were comparable between groups, except for a lower rate of preexisting diabetes mellitus in the ANA-positive group. ANA-positive patients had a lower incidence of proteinuria (89.3% vs. 96.0%, P = 0.03) and a trend toward higher incidence of elevated serum creatinine (33.3% vs. 22.5%, P = 0.06). After adjusting for confounders, ANA positivity was independently associated with lower odds of proteinuria (aOR = 0.28, 95% CI 0.10-0.80, P = 0.02) and higher odds of renal dysfunction (aOR = 1.81, 95% CI 1.01-3.23, P < 0.05). No independent associations were found with other pregnancy outcomes. Therefore, ANA positivity is independently associated with a distinct renal phenotype in EOPE-reduced proteinuria but increased risk of renal dysfunction-but not with overall disease severity. These findings suggest that ANA positivity may identify a subgroup of EOPE patients with altered renal involvement, warranting enhanced renal function monitoring and further investigation into the role of ANA in subclinical autoimmunity and long-term maternal health.