Acting Gov. Jane Swift was hospitalized Friday after experiencing headaches and nausea for two days, her spokesman Jim Borghesani said.

Swift, 37, will stay at Brigham and Women's Hospital overnight but no length of stay has been determined, he said. She entered the hospital after her doctor recommended she be admitted for observation.

Swift, originally elected lieutenant governor and named acting governor in April 2001 when Paul Cellucci was appointed U.S. ambassador to Canada, did not run for election and will leave office at the end of December.

The nation's youngest governor and the first female governor of Massachusetts, Swift also was the first U.S. governor to give birth while in office.

Her twin girls were born in May 2001, and her oldest daughter is 4.