Trish Staine has every intention of running a half-marathon in a couple of weeks, an impressive feat in its own right, but even more so considering Staine just gave birth to a baby girl she didn't know she was pregnant with.

Indeed, Staine's delivery comes as a surprise to both her and her husband, John, who had had a vasectomy after the birth of their first child. As one study estimates, about one in every 7,225 women finds out she is pregnant just moments before delivery. And although such pregnancies are rare, the reactions are almost always the same.

"Down in the E.R. they found a fetal heartbeat," Staine said Wednesday from her Duluth hospital room. "And I was like, 'no, that's not possible.'"

Within five minutes, Staine said, her baby girl was born. The couple has named her Mira - short for Miracle - and despite being five weeks early, doctors said Mira was healthy, weighing 6 lbs., 6 oz. and measuring 18.9 inches long.

Staine, 33, had run for two hours earlier that day in preparation for the June 22 Garry Bjorklund half-marathon. The only pain she reported experiencing was in her back, after the run Sunday evening. When she woke up the following day, the pain had intensified, becoming so excruciating her husband John said she was "screaming, crying and yelling out." At the time, the two thought it might have been a pinched nerve, kidney stone, or burst appendix.

The pain became so great Staine eventually had her husband call an ambulance. "I felt like I was dying," she said. "I didn't know what was going on."

Unknown pregnancies can perplex even the most experienced obstetricians and gynecologists, as the woman can totally miss the signs and symptoms she's pregnant. These include a missed period, breast tenderness, weight gain, bloating, constipation, and nausea.

Trish Staine, however, said she showed none of these symptoms. She had no missed periods, and her husband John said she even appeared to have lost weight during her training.

"Her face was even thinner," he said.

Staine's case comes a little over a year after a Tennessee woman, unconscious, was rushed to the hospital after having a seizure, and who later gave birth to a baby girl via cesarean section, despite not having known she was pregnant. Likewise, in 2010, a woman from Cedar Falls, Iowa gave birth to a girl of her own unexpectedly one morning. Doctors had to break her water for her, at which point, the woman said, her daughter "pretty much just fell out."

Neither of the two women experienced any irregularity during their pregnancies. Each reported having consistent menstruation, minimal discomfort, and feeling almost no movement from the baby. Any kicking or moving was likely chalked up to gas.

As for Trish and John Staine, the two said they're happy to add another girl to their family, which already includes four boys and a girl.

"My daughter's really happy. She finally has a little sister," Staine laughed. "She's the only girl, so now we have two girls. And a whole team of boys."

Staine said this whole ordeal has opened her eyes to the real possibilities of an unknown pregnancy, which she had previously written off as reality-TV nonsense.

"I've always been skeptical about all these TV shows with people saying 'I didn't know I was pregnant,'" she said. "You cannot be pregnant and not know about it. So as soon as I had her, I was like, 'I'm a believer.'"