She acted as regent for her son Gonzalo, who had been given the County of Aragon, and later was co-regent of the Kingdom of Navarre, along with her daughter-in-law Jimena Fernández and the bishops of Navarre, of her grandson Sancho III.
She was first married by her father to Ordoño III of León in 951. Fernán's support of Sancho the Fat cost her her husband's affection and she was repudiated in 956. By him she had two, and possibly three children:
^Alfonso Ceballos-Escalera (p. 159 de su obra Reyes de León: Ordoño III (951–956), Sancho I (956–966), Ordoño IV (958–959), Ramiro III (966–985), Vermudo II (982–999), editorial La Olmeda, Burgos, 2000 ISBN 84-89915-11-3)