AriSevin,
That is something that you will have to decide for yourself.
You have to understand that certain groups have “agendas”, and will often skew the reporting of “studies” to make their case sound more impressive. Midwifes and groups that are against anything except “natural methods” do not do ultrasounds, and feel that they should not be used. So, you have to read their literature with that in mind. Likewise, studies performed by the manufacturers of the ultrasound machines should also be taken with a grain of salt.
There have been a few studies which have shown certain effects of the ultrasound in the lab and in the clinical settings. But, these have not been reproduced in later, follow up studies. Currently, there have not been any studies which have actually shown any ill effects of fetal ultrasounds. Of course, those groups who are against the use of ultrasound will say that there have not been any studies which prove its safety either. But, this is misconstruing how research is actually conducted.
You can pull the articles from the literature and read them for yourself. Many times, what is reported by the people against ultrasounds is not really what the authors were saying. Often, statements are “taken out of context” or paraphrased. Also, these groups will “cherry pick” out certain articles which may actually show what they want, even if the studies are very old and have been shown in later studies to not be true. But, they seem to continue to quote these certain few articles, over and over again.
One article on the internet, written by a midwife, equates ultrasound to the use of x-rays. Yes, way back in the early part of the 20th century, x-rays were actually used in obstetrics to confirm pregnancy, follow growth, and many other reasons. Of course, as time went by, it was found that the overuse of x-rays (which use radiation), and their use in pregnancy, was not a good idea. And, the use was stopped. The midwife states that ultrasounds should be looked at the same way as the x-rays. That in the beginning, everyone says there is no risk, but that has never been proven. So, the midwife states that ultrasounds should not be used. This is sort of circular reasoning.
Although certain harmful effects can be produced in cells, in a laboratory setting with the use of high frequency sound waves (called in-vitro study), how does this actually translate to the possible effects in a complex organism like a human (called in-vivo study)? Just because certain things can be produced in a petri dish does not mean that that is going to occur in actual practice in a clinical setting. Another case of using data out of context.
Apparent ill-effects such as low birthweight, speech and hearing problems, brain damage, and non-right-handedness reported in small studies have not been confirmed or substantiated in more recent larger studies. But again, these older smaller studies are reported over and over by the groups against the use of ultrasound.
Most of the big health organizations are against multiple ultrasounds because of the cost involved to the health care system. They state, and rightly so, that obtaining multiple ultrasounds throughout the pregnancy does not really give any significant amount of information that could not be obtained by a thorough physical exam using a fetal stethoscope. So, these organizations cannot justify the use of multiple scans during the pregnancy.
Probably, the biggest risk in the use of ultrasound during pregnancy is the possible over- and under- diagnosis brought about by inadequately trained staff, often working in relative isolation, and using poor equipment.
It should be born in mind that prenatal ultrasound cannot diagnose all malformations and problems of an unborn baby, so one should never interpret a normal scan report as a guarantee that the baby will be completely normal. Some abnormalities are very difficult to find or to be absolutely certain about. The position of the baby in the uterus has a great deal to do with how well one sees certain organs such as the heart, face and spine. Sometimes a repeat examination has to be scheduled the following day, in the hopes the baby has moved.
Images tend also to be strikingly clear in skinny patients with lots of amniotic fluid, and frustratingly fuzzy in obese women, particularly if there is not much amniotic fluid as in cases of growth restriction. As in almost every endeavor, there is also a wide difference in the skill, training, talent, and interest of the sonographer. The improvements in equipment has also lead to the earlier detection of abnormal structures in the fetus bringing along with it "false positives" and "difficult-to-be-sure-what-will-happen" diagnosis that could generate huge amount of undue anxiety in parents.
So, again, this is something that you have to decide for yourself. But, having one or two ultrasounds during a pregnancy is probably just fine, without any significant risks. However, in life there are no guarantees.
There is probably no risk at having multiple ultrasounds, but if they are not really needed, why have them? Almost every mother wants to see her baby in the womb, so one scan is okay. But, to have repeat studies to determine the gender, the position of the baby in the uterus, to “see how things are going”, and so on, really cannot be justified.
Do your own research, analyze the data yourself, be wary of groups with agendas, and decide for yourself.
Good luck.