Utah Woman Gives Birth to 14-Pound Baby, What Caused His Massive Size? (PHOTOS/VIDEO)

Last May, Sarah Brandon of Utah gave birth to a 14-pound baby, Joel Brandon Jr., or "J.J.," by cesarean section, and was surprised by his massive infant size, ABC News reports.

"When they stuck him on the scale he was 14 pounds even," Brandon told ABC News. "The doctor said it was the biggest baby he had ever delivered."

Brandon's previous twin girls weighed 4 pounds each, a delivery experience that was markedly different from J.J.'s delivery on May 9 at Timpanogos Regional Hospital in Orem, Utah.

"I had to have two [obstetricians] deliver him instead of one, because they knew he was going to be big," she said. "They struggled to get him out."

J.J. spent the first 10 days of his life in the Neonatal Intensive Unit due to respiratory problems, but ever since he's left the hospital, Brandon says he's been "very calm, content and giggly."

"He sits with his sisters all day. He only cries if he's hungry or tired," she said. "He's an awesome little guy, or big guy."

Dr. Robert Barbieri, chief of obstetrics and gynecology at Brigham and Women's Hospital in Boston, explained that J.J.'s unusually large size was due to Brandon's condition of type 1 diabetes.

"An interesting effect of insulin, if it's not taken in a sufficient amount, the glucose remains high, and the baby's glucose starts to rise," said Barbieri. "It's like giving the baby fertilizer and it grows very large."

While a 14-pound baby is "extremely rare," Barbieri explained that one out of 1,000 babies could weigh 11 pounds at birth, while one out of 10,000 could weigh up to 14 at birth.

Click here to see photos of Sarah Brandon and her children, including her big baby J.J.