I read an article (I believe it was from a medical journal) a few years ago about possible dangers of ultrasound. It was the first time I had ever heard that there might be a question of the safety of ultrasound. At the time, I was about 35 weeks pregnant with my first baby and had already had a few ultrasounds, unfortunately.
It has been a few years since I read the article, but I will share with you what I can remember: The article was not stating definitive findings on the dangers, but more about the possibility of unknown dangers. The sound waves emitted during an ultrasound cause certain cells and tissues to expand during exposure to that sound. The problem is, we don't really know (yet) what that might do to a person. There appears to be no significant harm at this point, but again, it is an unknown.
Something that I also consider is that ultrasounds have not been around for all that long (maybe 40 years or so, I think?) so we don't really know about any long terms effects or consequences. Who knows, maybe 50 years from now we will find out that a prenatal ultrasound causes some terrible health problems that don't manifest until that baby is 60 or 70 years old. Just my own personal speculation (and I'm not a medical professional or anything). My personal view on medical procedures, interventions, etc. is "the fewer, the better."
I believe our bodies are designed to funcion best when allowed to work in their natural processes. Advances in medicine have opened up doors for lengthening and improving life when something goes drastically wrong, that our bodies are not able to manage naturally, but we have also turned many things into medical issues that, I think, may be better handled naturally. Pregnancy and childbirth is one of those areas where I think we have turned it into a medical procedure when, in 97% of all pregnancies, we are better off letting things go the natural course. For the other 3%, medical help is invaluable and can save lives and offer hope, but that is really a very small number of the cases.
Sorry if this is much more than you bargained for! I think I got on my soap box for a minute! If you are interested in the specific article that I mentioned here, let me know and I will see if I can dig it up somewhere.
Congratulations on your first baby!