Berthod, who turns 37 next week, was a Swiss downhill and giant slalom champion who won a World Cup downhill competition at Saint Moritz in 2002.
The athlete, who “outed” herself as a lesbian on Facebook last summer, on Tuesday used the social media platform to reveal her plans to wed Laetitia Calvi.
Berthod, who retired as a skier in 2008 after 12 years on the circuit, works in Sion in the canton of Valais as an ambulance driver.
Her partner is an anaesthetist at the University Hospital of Lausanne.
While same-sex marriages have gained acceptance in parts of Switzerland, Berthod comes from a Catholic family who regard such unions as sinful, the Blick newspaper reported online.
The newspaper quoted a friend as saying that Berthod’s father and brother had a hard time accepting her sexual orientation.
Although her skiing colleagues were aware of it, Berthod remained discreet about being a lesbian until last year.
In 2012, Swedish former alpine skier Anja Pärson “came out” in the same manner during a radio interview.
Two weeks later, Pärson surprisingly announced on Facebook that she had given birth to a son.
She has remained silent about who the father is but was in a relationship with another woman and together the couple was bringing up the boy, Schweizer Illustrrierte reported last year.
Berthod told Blick two years ago that she did not want to have children.
In a nationwide referendum in June 2005, the Swiss people backed a law that gives same-sex couples the right to register partnerships.
The law gives such couples the same rights as opposite-sex couples except with regard to the adoption of children and fertility treatments.
It also bans the facilitated naturalization of a foreign partner to become a Swiss citizen after six year of partnership abroad, unlike with a conventional marriage.
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