I have the same thing happen whether I'm pregnant or not. My doctor says its due to stress.
Hair is definitely affected during pregnancy and after. I actually had the opposite while pregnant . . . I grew extra hair and my hair was thicker than it had ever been. LOL It was a bonus to pregnancy. But then a few months after I gave birth, out it came and maybe less than I had before. Boo. The short stubble is new hair coming in most likely. Try not to scratch your head. And there is something a dermatologist can prescribe you that enhances hair growth in case after baby this continues. But in answer to your question, yes. Hair is affected by pregnancy. good luck