"Can ultrasound cause hearing problems for babies? My doctor told me that it could. I had an ultrasound each month during my first four months of pregnancy when I lived in South America, but I have not had an ultrasound since I moved to the United States. Also, every pregnant woman in South America has a three-dimensional ultrasound. I haven't heard about that in the United States."
There is no confirmed evidence that ultrasound causes hearing problems or has any adverse affect on the developing fetus. One poorly designed study done a few years ago suggested there was a risk of the babies experiencing hearing loss due to ultrasound, but the way the research was performed made many scientists think the conclusions were incorrect. Since then, no other scientist has been able to find the same results. Replication is one of the hallmarks of scientific research.
Most of my practice consists of performing ultrasounds, and I believe in the value of well-performed ultrasound in pregnancy. On the other hand, no research has proven that there is a benefit to having monthly ultrasounds either. I realize parents-to-be like to see their baby by ultrasound, but I can't fault your doctor for not doing monthly ultrasounds in a healthy pregnancy.
For "low-risk" pregnancies, I recommend one really thorough ultrasound at 16 to 20 weeks gestation (as measured from the last menstrual period) to look at the baby's anatomy and check for any problems with the heart or other major organs. I also recommend looking for the most experienced team with the best equipment in your area to perform the scan. The "team" may consist of a sonographer, or technician, who obtains the images and a sonologist, the physician, who interprets them. Many studies have shown that experience pays off in terms of the detection rate of problems; those who see a lot of problems day in and day out are more familiar with how things should or shouldn't appear.
Many insurance companies now cover one ultrasound in uncomplicated pregnancies. Some insurance companies in our area require that the ultrasound be performed only in places accredited by independent groups s. Don't be afraid to ask if the practice examining your baby is accredited.
As for 3-D ultrasound, it is an exciting development in technology, but not standard at the present time. I am one of a number of doctors who specialize in ultrasound who are working with 3-D ultrasound to determine its proper role. Three-dimensional ultrasound uses computer technology to reconstruct the ultrasound image beyond the usual thin slices we obtain with a standard prenatal ultrasound. The pictures can look like sculptures rather than two-dimensional paintings. Right now we consider 3-D something that may be useful in addition to standard imaging, but it is not a requirement for standard care.