Adds details and background throughout

May 21 (Reuters) - Oura, the maker of Oura Ring, said on Thursday that it has confidentially filed to go public in the United States.

The U.S. IPO market has bounced back strongly after a brief lull in March, as investors look past geopolitical uncertainty and plough money into new listings.

Oura, which traces its roots to Finland, makes the Oura Ring, a smart wearable that tracks sleep, activity and other health metrics, offering personalized wellness insights and guidance.

In October, Oura raised over $900 million at a valuation of about $11 billion in a funding round led by Fidelity Management & Research Company.

Confidential filings with the U.S. securities regulator allow companies to prepare for IPOs away from public market scrutiny.

The number of shares to be offered and the price range for the proposed offering have not yet been determined, Oura said.