The previous record holders are Thomas and Grace Houghton-Burnett, who weighed 10lb1oz and 8lb2oz when they were born in 2002.
Beth revealed that she had a gut feeling that her twins were going to be large, as her other four kids also weighed more than 9lb at birth.
The 35-year-old student nurse was herself born heavy at 11lb13oz.
"Large babies run in the family so I knew that they were going to be pretty big. But none of us expected them to be quite so large," the Daily Mail quoted Beth, as saying.
Beth was in labour for four hours before the twins were born at Burnley General Hospital in Lancashire last week.
"I was absolutely enormous in the weeks running up to the birth and it was so uncomfortable," she said.
Her other children were all large, with the eldest Emma, now 17, weighing in at 9lb9oz, Leah, eight, born at 10lb11oz, Lauren, five, 9lb11oz and Callum, three, at 12lb1oz.
However, Beth, who lives with her husband Steve in Rawtenstall, said that their children were now of average size, despite their large birth weights.