A woman in Iowa gave birth to a baby weighing 13 pounds and 13 ounces, without undergoing surgery or taking any painkillers.

Kendall Stewardson's baby boy, Asher - measuring 23.5 inches - was born last Thursday at Mercy Medical Centre in Des Moines, Iowa. Fifteen months ago, his 'big' brother, Judah, arrived weighing 12 pounds and an ounce at birth.

Mercy officials say only a tenth of 1 percent of all newborns weigh more than 11 pounds at birth, CBS news reported.

Stewardson endured six hours of labour without an epidural injection. She says she and her husband, Joshua, wanted to avoid caesarean delivery because that wouldn't have been good for her or Asher.

According to the Guinness Book of World Records, the biggest newborn baby ever was born to Anna Bates of Canada in 1879, who weighed a whopping 23 pounds, 12 ounces, but died 11 hours later.