Ukrainian Iryna Nohai and her South African fiance Emlyn Culverwell were arrested in Abu Dhabi after a doctor discovered Ms Nohai was pregnant.
Sex outside marriage is illegal in the religiously conservative Gulf nation.
Mr Culverwell's mother had pleaded for their release, saying "the only thing they did wrong was fall in love".
Describing the phone call she received from her son on Friday to say that the charges had been dropped, Lynda Culverwell told South African media: "I didn't know if I wanted to scream or cry."
"I'm dreaming about my grand-babyâ€š" she added in an interview with the Times Live news website. "I have to resist calling them every two minutes."
Iryna Nohai, 27, had gone to hospital, suffering from stomach cramps.
But a local doctor reported her to the authorities after discovering she was pregnant.
When the pair failed to produce a marriage certificate they were arrested in the hospital.
South Africa's International Relations Department, which had said it was unable to offer the couple any help in the case, confirmed news of the release to local media.
A couple jailed for a month in the United Arab Emirates (UAE) over "unlawful sex" have been released and the charges against them dropped.