Aceh is the only province in the world's most populous Muslim-majority country that imposes sharia law. People can face floggings for a range of offences -- from gambling, to drinking alcohol, to gay sex.
The woman was among 13 people -- seven men and six women aged between 21 and 30 -- who were caned Monday at a mosque in the provincial capital Banda Aceh, as a baying crowd cheered the spectacle.
Six couples were found guilty of breaking Islamic laws that ban intimacy, such as touching, hugging and kissing, between unmarried people.
A man was caned for a less serious offence described as spending time with a member of the opposite sex in a hidden location in a fashion that could lead to adultery.
One 22-year-old woman due to be flogged was given a temporary reprieve as she was pregnant -- but Aceh Deputy Mayor Zainal Arifin pledged: "The punishment will be handed down after she gives birth."
The official added that he hoped the canings would serve as a deterrent: "We hope there are no more people in Banda Aceh who break the law in future."
More and more people are being caned in Aceh, with a particular increase in recent times in the number of women being flogged.
Aceh, on Sumatra island, began implementing sharia law after being granted special autonomy in 2001, an attempt by the central government in Jakarta to quell a long-running separatist insurgency.
Islamic laws have been strengthened since the province struck a peace deal with the central government in 2005.
More than 90 percent of Indonesians describe themselves as Muslim, but the vast majority practise a moderate form of the faith.
