I have asthma. The first 5 years of my life were really hard, almost every week my parents took me to the hospital because I couldn't breathe. When I was 5 I had a severe asthma attack and I stayed on hospital for 2 weeks. I don't remember much from that time but my mother told me when I started to recover I didn't talk and when I finally talked I stuttered. The doctors said that I realized that I have a serious health problem and that made me anxious and always aware of it. So yes I believe that stuttering can be caused by trauma.