Bristol Palin and her son, Tripp. (Richard Knapp/2012 A&E Television Networks)

That’s less than half the 1.8 million viewers who had watched the show Lifetime telecast immediately before the debut, “Dance Moms.”

Among women 18 to 34, “Life’s a Tripp” plunged 50 percent compared with Lifetime’s previous four-week average in the time slot; the story was much the same among women 18 to 49 and 25 to 54.

“Life’s a Tripp” is a rare misstep for the Palin reality-TV dynasty.

Back in September 2010, Bristol Palin’s debut helped ABC’s “Dancing With the Stars” attract more than 21 million viewers.

Her guest-star gig on ABC Family’s “The Secret Life of the American Teenager” logged nearly 3 million viewers in July 2010.

And Sarah Palin’s reality-series debut on TLC’s “Sarah Palin’s Alaska” attracted about 5 million viewers, which was a record for that network back in November 2010.