"There was no female detainee release today," the spokesman for the US detention facility in Iraq told news service AFP.
"Today's release was done after a review by the joint board and at this stage I cannot offer any other details."
Four women remain in detention.
Authorities released more than 400 detainees last month, including five women.
The move was widely seen as a response to demands from the kidnappers of US reporter Jill Carroll – the group calling itself the Brigades of Vengeance had demanded freedom for all female prisoners in Iraq.
Both the US and Iraqi spokesmen strongly denied any link at the time.
But shortly after those releases, a new videotape from the kidnappers was broadcast by Arabic television channel al-Jazeera in which they reaffirmed their demands.
Ms Carroll, who was writing for the Christian Science Monitor, was abducted in Baghdad on January 7 as she travelled to a meeting with a leading Sunni Arab politician.
Her fate, and that of German engineers Rene Braeunlich and Thomas Nitzschke, who were abducted in the northern refinery town of Baiji, remains uncertain.
An ultimatum from the captors of the engineers threatening to kill them, unless the German government cuts all links with Baghdad, expired on Friday night.
Security clampdown
Meanwhile, tight security is in place for the run-up to the main Shiite festival, the 10-day Ashura commemoration.
The annual festival is a regular target of Sunni rebels.
Insurgents killed nine people, including two policemen, in a series of attacks on Sunday.
They included five civilians killed when their minibus hit a roadside bomb south of Baghdad.