LOS ANGELES, June 21 (Reuters) - Bristol Palin tripped up with TV audiences after less than 750,000 people watched the first episode of her new reality show.

Palin, who found fame in 2008 as the accidentally pregnant unmarried daughter of Republican conservative U.S. vice-presidential contender Sarah Palin, chronicled her life with her now three-year-old son Tripp in the Lifetime show "Life's a Tripp."

But according to audience figures on Thursday, just 726,000 watched the show when it debuted on Wednesday. By contrast, some 3.3 million watched the latest installment of MTV's "Teen Mom" reality series on Wednesday.

"Life's a Tripp" got unenthusiastic reviews from TV critics and proved no match with the U.S. public for the polarizing but charismatic Sarah Palin. The 2010 TV series "Sarah Palin's Alaska" attracted some five million viewers on its first outing, but was canceled after one season. (Reporting By Jill Serjeant; Editing by Paul Simao)