straight from the source Is Ultrasound safe? Is there a limit to the number of images that should be taken?
However, everything is controversial. There is a misunderstanding as to the purpose of science. People think science is going to tell them the truth. It's not. Science is a series of hypothetical statements that can potentially be disproven. If scientists try to disprove a hypothesis but can't, they will generally accept the hypothesis. But it's still open to testing and may eventually be disproved. Hence, science is really a series of progressively better and better hypotheses. That is why scientific opinion changes regularly. Scientists are supposed to be open-minded.
At the present time, it is http://sevenhillsglass.com.au/?mikstyis=site-de-rencontre-fran%D0%93%C2%A7ais&920=c6 generally accepted by scientists that ultrasound is perfectly safe.
This view is corroborated by the Mayo Clinic, which states, "Diagnostic ultrasound has been used during pregnancy for many years and is generally considered safe when used appropriately."  The doctors at the Albert & Parliament Primary Health Care Centre agree with this opinion. In fact, we are not aware of any medical doctor who disputes that view.
Furthermore, in our opinion, this website ultrasound is safe, when performed correctly, regardless of the number of images taken.
According to WebMD, "An ultrasound is generally performed for all pregnant women around 20 weeks into her pregnancy. During this ultrasound, the doctor will confirm that the placenta is healthy and that your baby is growing properly in the uterus. The baby's heartbeat and movement of its body, arms and legs can also be seen on the ultrasound." There are other benefits to ultrasound, as well. 
In our view, women who wish to take advantage of these benefits should feel free to do so.
The doctors at the Albert & Parliament Primary Health Care Centre, practice evidence-based medicine. We want our patients to be well-informed about the medical procedures they are considering, so that they can make decisions that are in their own best interest. We welcome your feedback in relation to this article and all the other articles on this website.