Actually, used cat litter is dangerous for both pregnant women and cancer patients in real life. I've been both; a recent severe cancer survivor strictly instructed to remove any and all litter boxes from our house while I was going through chemo therapy and recovering from it, and I was instructed not to clean our cat litter while pregnant with my son.
The ammonia and bacteria in the used litter pose a very large health threat to people, and fetuses, with weak or developing immune systems.