Bertha Olsdotter was born on June 14, 1841 in the small town of Valby in Kyrkheddinge, Malmohus, Sweden. She was the third of six children.

Her father and brother joined the Church of Jesus Christ of Latter-day Saints in 1854. Later, Bertha, her other siblings, and her mother followed suit in 1856. This prompted the family to follow her older brother and to emigrate to Utah in 1857. Bertha was only fifteen when she made the journey to the United States.

In Utah, on January 31, 1859, Bertha married August Swenson, another Swedish immigrant, and the couple settled in Spanish Fork, Utah. Bertha had thirteen children over the course of the next twenty-seven years, ten of which survived into adulthood.

As part of her husband's calling in the Church, the family briefly relocated to St Joseph, Rio Virgin, Utah. When the county was given to Nevada, they moved back to Spanish Fork. Bertha was a steady presence in her family even when her husband was put in jail for practicing polygamy. She was sick for years before she died on June 26, 1898, at the age of fifty-seven years old.