Jayden Sigler weighed in at 13 pounds, 14 ounces, when the healthy boy was delivered Thursday by cesarean section, the North County Times reported Saturday.
His mother, Cynthia Sigler of Vista, said that her immediate reaction was: "How'd he fit?"
Doctors initially estimated that Jayden would weigh about 9 pounds, but that number jumped to 11 by early March, the mother told the newspaper.
Dr. Jerald White, who delivered the baby at Tri-City Medical Center, said Jayden was the biggest of the 20,000 newborns he has helped usher into the world since he started in 1961. The doctor said delivering a very large baby via cesarean section is more challenging, but "it wasn't so difficult that it created a problem for anybody."
While Jayden will likely make a big dent in the doctor's memory, he's small compared to the largest baby ever delivered: a baby born at 23 pounds, 12 ounces in January 1879, according to the Guinness Book of Records. That newborn was said to have died 11 hours after birth.
The largest surviving birth, according to Guinness, was a boy born in 1955 who weighed 22 pounds, 8 ounces.
But Jayden's weight hasn't lost its shock value to Sigler's family. She said her cousin didn't believe her until she showed a photo of the scale readout.
Jayden's birth weight is almost twice that of his sister, Jailyn, now 2 1/2. She was 7 pounds, 2 ounces at birth.
Sigler said she'll have to exchange all the baby clothes she bought for larger sizes.