Background and objectives: For decades, dengue outbreaks have been affecting vast territories of the Americas. In 2010’s decade, Chikungunya and Zika virus (CHIKV and ZIKV) emerged as new arboviruses in the region. While several seroprevalence rates have been reported for dengue virus (DENV) infection in Brazil, serological surveys for the latest are scarce. We aimed to evaluate the seroprevalence of CHIKV, ZIKV, and DENV infections in pregnant women at admission to a public maternity hospital of Nova Iguaçu, state of Rio de Janeiro. Methods: A simple questionnaire was applied, containing limited demographic, obstetric, and clinical data, alongside with blood collection. Different commercial test kits, based on enzyme-linked immunosorbent assay (ELISA), were used. Results: Among 349 pregnant women enrolled from July to December 2017, there was a 28.4% seroreactivity for CHIKV, 47.2% for ZIKV, and 88.8% for DENV. Conclusion: These findings reflect the high dengue endemicity scenario and suggest a significant reach of the recent outbreaks of ZIKV and CHIKV infections in the region.