Channel-surfing through the cable TV graveyard the other night I came across a TLC show called “I Didn’t Know I Was Pregnant.”

It’s a 30-minute weekly reality program featuring reenactments of “surprise” pregnancies.

These women didn’t know they were pregnant until well into their terms. One woman, according to the show’s Web site, was clueless not once but twice.

At first blush, one tends to be incredulous about this sort of thing. How can someone be pregnant and not know it until they’re darn near dilating?

And then I flashed back on the Harnitz family of Mankato, which gained a certain measure of notoriety in 1985 for the same thing.

In Esquire magazine’s annual Dubious Distinction Awards that year, 41-year-old Sharon Harnitz’s surprise birth was duly noted along with other tales of the bizarre.

She and husband Detlef “Dutch” Harnitz already had two children — 20 and 17 — when she unknowingly became pregnant.

Sharon was large-framed and didn’t suspect anything because she had only gone up one clothing size. And when her menstrual periods became light, she chalked it up to early menopause.

Yes, she experienced discomfort, but dismissed it as a possible bladder infection.

Sharon was at home one September night when she began having abdominal pains. She went into a bathroom, looked at herself in a full-length mirror and saw a protrusion.

It was a baby’s toes.

“He was just putting his best foot forward,” Dutch said afterward of the birth of 6-pound, 9-ounce Cory.

“I was in shock,” Sharon said, recalling the moment of truth.

Dutch handed out celebratory cigarettes to his factory work buddies the next day as he told them of the out-of-the-blue birth.

His co-workers thought he was pranking them and waited for the punch line that never came. When they became satisfied he was telling the truth, they pelted him with earthy barbs — none that could be printed, Dutch said.