Low white blood cell count

Crystal • Married for 5 months together for 7 years, pregnant with baby 1. Scared to death!
Just got a call from my OB that I have to go see a hematologist because my white blood cell count is so low, anyone have this/had this and everything was okay? Hopefully it's just due to my Hashimotos disease and nothing more. I'm nervous now though. Hope my sweet girl is okay.