A heartless Pennsylvania woman gave birth in a bar bathroom, and then left the helpless infant to die in a toilet while she watched pro wrestling and smoked a cigarette, authorities said.

Amanda Catherine Hein, 26, was held without bail yesterday after being charged with one count of criminal homicide stemming from the Aug. 18 tragedy.

A late-night cleaning crew found the infant’s body in a toilet tank at Starters Pub in Bethlehem, about 30 miles north of Philadelphia.

“I cannot get inside this lady’s head,” Northampton County District Attorney John Morganelli said of Hein’s potential motive.

“I have no clue.”

The premature baby was a few weeks premature, but still could have survived, authorities said.

But Hein allegedly put the newborn in a plastic garbage bag and stashed it in the toilet tank.

After giving birth, Hein allegedly smoked a cigarette and rejoined friends, gathered to watch the pay-per-view wrestling show “WWE SummerSlam.”

The Allentown resident had kept her pregnancy a secret.

The suspect’s stepmother, Louiseann Hein, sobbed when she learned the horrific details. She didn’t know Amanda was expecting, but recalled seeing a letter from Planned Parenthood addressed to her.

“I told her she always had a home here,” Louiseann Hein told The Morning Call newspaper.

“We would make room. Would find a way.”

Hein was interviewed by cops on Aug. 20, and she admitted to giving birth and placing the baby in the toilet tank, officials said.

With Post Wire Services