How do i tell my Hubby thn I'm pregnant?

i am 6 weeks preg now i tried telling my hubby tht i'm pregnant but he thinks tht i'm bluffing and he is afraid tht he cant afford for another baby. at the moment we have 1 son who is almost 2 years old i really wan this baby but how do i make him understand tht it is tru tht i'm preg n we really shud keep the baby.