Janice Dickinson's son NATHAN FIELDS has begged his mother to stop having plastic surgery - because he's afraid excessive operations will ruin her looks. The 20-year-old - who is the former supermodel's son from her marriage to movie producer Simon Fields - has pleaded with 52-year-old DICkinson to quit her "obsession", because he thinks she is already beautiful. He tells British magazine Closer, "We've made a deal that from now on there will be no more. Well, she's said she won't touch the face at least. I'm not sure whether I believe her - she'll just do what she wants anyway. "I just don't think she needs surgery. She's a beautiful lady and doesn't need anything worked on. But we're talking about a woman who's on quest for eternal youth." DICkinson recently underwent a brow and neck lift and has confessed to spending up to $100,000 (GBP50,000) on cosmetic surgery.