In June 2008, the Obama campaign - in an attempt to disprove another set of internet rumours that Mr Obama's middle name was Muhammad - made public his birth certificate.
The document - a Certification of Live Birth - indicated that Mr Obama had been born at 7.24pm on 4 August 1961, in Honolulu, Hawaii.
Researchers also dug up birth notices for Mr Obama printed in the Honolulu Advertiser and the Honolulu Star-Bulletin in 1961.
The newspapers received information about births from Hawaii's Department of Health.
But Mr Obama had never released his original "long-form" birth certificate until now.