Urine smells like cats litter box?

My pee smells like my cat's litter box. I read that the scent would be increased ammonia. Would being on keflex create a higher ammonia content in my urine? I was on keflex for 10 days and finished about 5 days ago. Could it be from pregnancy? I had unprotected sex last Thursday, so 8 days ago and I haven't tested yet.