Mom gives birth to surprise baby at 31 weeks after mistaking pregnancy for kidney problems

(INSIDE EDITION) - A mom received quite the surprise when she learned she was nearly eight months pregnant after a kidney scan and gave birth hours later.

Leanne Allen, 37, already has two children and after suffering a miscarriage in January, she and her husband decided they did not want any more children and he had a vasectomy.

When Allen began experiencing fatigue, swollen legs and kidney problems, doctors called for an MRI, but the results left them stunned.

"She then said she had found something on the scan that she needed to tell me. Straight away I was panicked, thinking she had found a tumor," Allen said. When she then told me I was pregnant I nearly fell off the bed. And when she went on to say I was 31 weeks, I just went into shock.

Thirty hours later, baby Harley was born through C-section. Doctors had the fast delivery due to Allen having pre-eclampsia, a potentially fatal pregnancy complication.

"It was all so much of a shock and happened so fast that we didn't want to tell anyone until we knew she was fine," Kevin Allen, Allen's husband, said. "We literally went from kidney scan, to being pregnant, to having a baby in 30 hours. I still can't believe I'm a new dad again."

The couple didn't even have time to tell their kids Jayme, 14 and Mitchell, 12, about the family's surprise new addition before she was born, so they surprised them both in the hospital.

They broke the news on camera, telling them they wanted to show them "what had been making mom ill" before revealing a photo of Harley.

In a video shared by SWNS, they showed their children a picture of 3-pound, 8-oz. arrival, who is recovering in the NICU.

Jayme and Mitchell are shocked at the news and have been left utterly speechless.

"Touching her tiny head that first time was so amazing, I loved her so much already, despite only knowing she even existed for two days," Allen said.

The family hopes their daughter will be home from the hospital in a few days, adding that she is steadily progressing. Harley doesn't have any long term effects from Allen not knowing she was pregnant, the family said.

"It's just absolutely mind boggling to think that a week ago how different our lives were," Kevin said. "It has been a whirlwind of emotions. Harley is an absolute miracle."