Regina Loss grew up in a Polish Jewish family. She lived with her parents Franciszka and Grzegorz and her brother Adam in Gdynia, where her father ran a wholesale citrus business. After the war began in 1939, they returned to Regina’s birthplace of Baranowicze (now Baranavichy).
After the Germans occupied Baranowicze in 1941, Regina Loss was physically abused by German soldiers. In the fall of 1941 the family had to move to the ghetto, where they were subjected to repeated raids. When Regina’s father was murdered during one raid in 1942, Regina Loss fled the ghetto with her mother and brother. They then hid in nearby villages. The Tatar Chazbijewicz family and other Polish and Belarusian farming families helped them with food and accommodation. However, they frequently had to hide in forests or fields due to police checks.
The Loss family returned to Baranowicze in 1944. In 1945 Poland had to cede its eastern territories to the Soviet Union, and Baranowicze became part of Belarus. Franciszka, Adam, and Regina Loss therefore moved to Poland. From 1949 they lived in Gdańsk, where Regina Loss married Jerzy Fisior in 1953.