A woman from Littleton, Colorado, learned she was five months pregnant with a baby boy Thursday after visiting a walk-in ER to determine the source of her abdominal pain, according to reports. Despite having zero pregnancy symptoms, the woman was then informed she was going into labor moments after her discovery.

Amy Littlefield, 25, gave birth to her second child nine months and one day after the delivery of her firstborn, which she was still breastfeeding. Littlefield's son was not ready to come, however.

"I woke up the morning of Sept. 14, his birthday, with lower abdomen pain," Littlefield said Friday to CBS affiliate KCNC-TV. "I knew something was really wrong so I called my mom and said 'Hey, I think I need to go to the hospital something's happening.' We have a family history of ovarian cysts rupturing after birth."

Littlefield was positive that ovarian cysts were the source of her pain, which is why she was surprised to learn she was expecting a newborn child. Littlefield initially begged to differ, however.

"I thought he was joking. I said, 'No, no I'm not.' I said, 'I'm not pregnant,'" Littlefield said.

Littlefield was preparing to go into labor moments later, but the staff at the Swedish Medical Center weren't well-equipped to handle premature childbirth. This led the walk-in facility to call for an AirLife crew to help transport Littlefield to the Neonatal Intensive Care Unit (NICU) and Rocky Mountain Hospital for Children (RMHC). The walk-in ER, however, managed to deliver the baby before the AirLife crew had arrived.

Her son, Cayden, was born weighing only one pound and 10 ounces. He was immediately taken to the NICU, where he would spend the next three months receiving around the clock care, according to Fox News affiliate KDVR.

Cayden has a heart murmur, which is common among premature babies. He now weighs five pounds and will be able to go home for the first time soon. Littlefield was grateful for the nurses' help at RMHC as she said: "Everyone at the hospital said he wouldn't be here if it wasn't for you guys," according to NBC affiliate KUSA.

Denied pregnancy happens more often than one would think as nearly 1 in 2,500 women could not realize that they are pregnant. It's common for a woman to make it to 30 weeks without knowing that she's expecting, whereas Littlefield was 25 weeks in when she learned of her pregnancy. Pregnancies of this caliber aren't unheard of in her family, however.

"My grandma didn't know she was pregnant with my aunt until 5 months," Littlefield said Thursday to KUSA. "My mom didn't know she was pregnant with my older brother at 5 months."

Surprise Pregnancy
A Colorado women believed she had a ruptured ovarian cyst, but discovered she was five months pregnant and in labor. A pregnant woman is pictured holding her stomach June 7, 2006 in Sydney, Australia. Getty Images