I personally don't want an ultrasound. They are inaccurate, possibly dangerous, and won't reassure me or alarm me. However, my husband is still a little uncomfortable about my choice to birth at home unassisted. I think it would put his mind at ease if I had one, which would help promote good positive energy at the birth and during the pregnancy. Do you think that a single ultrasound at 20 weeks will harm the fetus, or do you feel that it is repeated exposure to ultrasound that mainly is dangerous?