The ultrasound test in pregnancy provides obstetricians with a unique opportunity to evaluate the fetus at different stages of his or her development. It has become an increasingly common method for determining the growth rate of the fetus with many doctor's office having the ultrasound equipment right in their offices. No x-rays are used, only sound waves. As far as we can tell to date, ultrasound is perfectly safe. Still, this procedure should be performed only when the information obtained will help in the prenatal care of your unborn baby.
There are numerous indications for having ultrasound. I will only mention several of them here:
You can even see what sex your baby is! Although, you may want to find out the old fashioned way - in the delivery room!