The woman, from Canton Vaud in the French-speaking southwestern part of Switzerland, will become a grandmother when her 20-year-old daughter gives birth to a baby boy expected in six weeks.
The woman, identified only as Cleonice by the daily 20 Minuten newspaper, had her daughter at age 14.
"I've always told my daughter that she should wait to have children, but obviously she has not listened to me," the paper quoted Cleonice as saying.
The newspaper also quotes Cleonice’s husband, Philippe, as having welcomed the surprising news.
"My wife works in a nursing home. In the future, it will be a grandmother taking case of other grandmothers - I like it. "
The paper said in Switzerland’s most recent case, a 32-year-old woman in Aargau became a grandmother in 2006.