The Colorado woman who allegedly ripped out the unborn baby from a pregnant mom had pretended to be expecting herself — even planning to meet her husband for a prenatal appointment on the day of the horrifying knife attack, authorities said.

But when Dynel Lane’s husband arrived to pick her up at their Longmont home Wednesday, he discovered her soaked in blood — her telling him she suffered a miscarriage — and the gasping baby lying in a bathtub.

Her husband rushed her to a hospital, where she was arrested on suspicion of attempted first-degree murder and other crimes after being accused of luring the unsuspecting victim, Michelle Wilkins, 26, with a Craigslist ad for baby clothes.

The baby did not survive.

The shocking case has sparked a debate over when a fetus can legally be considered a human being.

District Attorney Stan Garnett said he will wait for the results of an autopsy to decide what charges to file.

While drifting in and out of consciousness, Wilkins, who was almost eight months pregnant with a baby girl, told cops she did not know Lane before going to her home for the clothes, authorities said.

A doctor told cops the cut in her belly was performed well and would have required research on Caesarean births.

Wilkins managed to call 911 and cops arrived after Lane and her husband left for the hospital.

Her family released a statement to thank first responders and others, the Denver Channel reported.

“Thanks to everyone for the outpouring of sympathy and support,” they wrote.

A judge ordered Lane to be held in jail on $2 million bond. Her attorney, Kathryn Herold, did not comment at the hearing.

Under Colorado law, Lane could only face a murder charge if the baby was alive outside the womb.

Garnett would not comment on whether mental illness may be a factor in the case — but said his office is investigating Lane’s history.

One of Lane’s two teenage daughters told cops Lane showed her an ultrasound photo of a baby boy in December 2014, authorities said. The girl said she couldn’t tell her mom was pregnant, but the girl said her mother kept photos of herself appearing pregnant on a cellphone.

Lane, who has an expired nurse’s aide license, and her former husband lost a 19-month-old boy in a drowning accident near Pueblo in 2002, said her ex-father-in-law, Aaron Cruz.

Meanwhile, the emergency dispatcher who took Wilkins’ frantic 911 call said it was the most shocking of her 15-year career, the Denver Post reported.

Beth Kemper, 53, was near the end of her 10-hour shift when she answered the dramatic call from Wilkins, who lay in the basement, bleeding from her abdomen.

“I just happened to be the one who picked up the phone,” Kemper told the paper. “She saved herself. She’s a rock star, that lady.”

But the dispatcher herself rose to the occasion.

Throughout the call, Kemper remained calm, telling Wilkins to “get a towel or anything you can get in your hands and press.”

“You stay with me, don’t go to sleep,” Kemper said four times. “Don’t you go to sleep.”

With Post Wires