Urine test

Zayda
Hello everyone 
I went in for a urine test today because I have a cold but I was having symptoms of a urinary tract infection. My doctor told me that I had white blood cells (leukocytes) in my urine and that she would be testing it. Is it more likely that this means I have a UTI or a possible sexually transmitted disease? I am so nervous and I hope that it is something not so serious, I really want a healthy pregnancy!