Hearst Corporation bought Seventeen from rival US publisher Primedia last week for $182m (£114.1m).
Reports this week in the UK have suggested that Hearst is already planning a UK edition of Seventeen, which would sit alongside CosmoGirl. However, there has been no official suggestion that there are such plans.
Mansfield, president and chief executive of NatMags and a director of Hearst, said it was too early to decide on future plans for the new acquisition.
"Once the acquisition is complete, the first priority is the incorporation of Seventeen into Hearst magazines in the US. All future international decisions will be decided on at a later date," he said.
The magazine, launched in the US in 1944, has a circulation of 2.5m compared with the 1.06m circulation of the US version of CosmoGirl. Seventeen is the largest monthly beauty and fashion magazine in the US for 12- to 24-year-old girls.
At the time, Hearst president and CEO Victor Ganzi, said: "For Hearst, it is a strategic investment because of its scale and potential alongside our other US and international magazine businesses."
CosmoGirl has so far not made a huge splash in the UK teen market, with a circulation of 142,076 at the last set of ABCs, down 18.9% period on period.
CosmoGirl is up against rival teen monthlies including Hachette's Sugar, with a circulation of 321,258, Emap's J-17, with an ABC figure of 143,308, and Bliss, which has a circulation of 260,102.
Hachette also publishes teen title ElleGirl, which launched at the same time as CosmoGirl and has not yet reported an ABC figure.
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