April Branum, 39, of Garden Grove, just south of Los Angeles, went to a local emergency room on February 26 with stomach pain only to discover she was pregnant with a full-term fetus.
Doctors discovered the baby as they took X-rays of Branum's abdominal area and referred her to UCI Medical Center in the nearby city of Orange, California, for prenatal testing, said Susan Mancia, a spokeswoman for UCI Medical Center.
No defects were detected and two days later on February 28, Branum gave birth by caesarean section to a healthy, 7-lb 7-oz (3.4 kg) boy named Walter Scott Edwards III.
"I'm tired but happy. The happy cancels out the tired part," Branum told Reuters, adding that she had struggled with unsuccessful gastric bypass surgery performed seven years ago when she weighed about 500 pounds (225 kgs). She said it did not help her lose as much weight as hoped and left her with a lot of sagging skin.
"That's exactly where the baby was hanging out. He was in the skin and that is why I didn't feel him," she said.
Branum lives with her fiance, Walter Edwards II, in Garden Grove. She said she gave up hope years ago of having children.
"I thought I was hitting early menopause," she said. "I never had morning sickness or anything that came with pregnancy."