An off-duty NYPD officer was busted Monday on charges stemming from an incident in Queens with his ex-girlfriend, who’s five months pregnant, according to authorities and the alleged victim’s mother.

Officer Niall O’Doherty, 34, was arrested around 6:45 a.m. for the May 16 incident involving his former flame at College Place and 9th Road in College Point, police said.

The cop also faces three counts of aggravated harassment, two counts of harassment and one count of assault.

O’Doherty’s ex-girlfriend is pregnant with his child, the woman’s mother, Lorraine Walsh, told The Post on Monday morning.

The pair has known each other for six years and dated for a year-and-a-half, Walsh said.

Now, the mother-to-be is seeking an order of protection against her ex-beau at a Queens Family Court hearing set for 11 a.m. Monday.

“He was supposed to be there,” the victim’s mom said. “How’s he going to be there if he was arrested?”

“He’s not a drunk,” she added, shaking as she waited for a cab to the courthouse. “But he’s got a lot of problems. We can’t really talk about it.”

The criminal charges are the result of a “confidential investigation,” police said.

Further details of the circumstances surrounding O’Doherty’s arrest were not immediately available.

He has no prior arrests, authorities said.

Two women who said they know O’Doherty were completely unaware of his arrest.

“I think it’s some kind of error,” an older woman said outside a Bayside address listed for the officer. “This must be a mistake.”

“What are you doing?” a younger woman snapped at her. “Don’t talk to the press!”