It may put you at ease to be tested for exposure. If you've already been exposed then its not an issue. If you have not already been exposed then you are not likely to if you've had your cats that long and they never go outside. You're more likely to be exposed by gardening than from your cats.
FWIW, my DH travels extensively for business, so I had no choice but to change lots and lots of cat litter through all my pregnancies.
Beth, mom to older DD (8/01) and younger DD (10/06) and always missing Leah (4/22 - 5/1/05)