Brígida Ruiz was born in Cordillera Department, Paraguay, on 8 October 1907. At the age of 15, she married Miguel Cuevas. Her husband later fought in the Chaco War (1932–35). The couple had eight children. Her husband died around 1980.
Ruiz lived with her daughter Regina until April 2014, when Regina suffered a heart attack, and Ruiz moved to live with her granddaughter, María Cuevas de Orué (aged 59 in 2016). At the time, she attributed her longevity to the love she received, and to her methodical diet that included coconut, milk, fish and honey (she never consumed refined sugar). Her relatives reported that she didn’t suffer from any type of disease, so she was not taking any medication as a centenarian.
As of October 2016, she had one living daughter Regina (aged 71), 37 grandchildren, 67 great-grandchildren, and 12 great-great-grandchildren.
Brigida Ruiz de Cuevas died in Loma Grande, Cordillera Department, Paraguay on 1 October 2018 at the age of 110 years, 358 days.
Following the death of 111-year-old Silverio Pereira Ayala on 30 May 2018, she became the oldest known (documented) living person in Paraguay.
Her age was verified by Stefan Maglov, and validated by the LAS on 2 November 2020, becoming the first validated supercentenarian who died in Paraguay, and second overall (after Casilda Benegas who died in Argentina).