Echocardiogram for the baby?!?

We have to go see a pediatric cardiologist because they haven't been able to see all of the baby's parts of the heart. My doctor said it's just to make sure nothing is wrong, and they have no indication that anything is wrong. They just want to know for sure. I've had 3 extra sonograms because I have gestational diabetes and they said they just haven't been able to see what they need to see. I know they said not to worry but I find it strange to send me to another specialist when I'm going to have many more sonograms before the baby gets here. Why not just wait until next time to see of they can see it then.... I don't know....I have none of the risk factors that I can find to have this procedure done. It just seems weird to be taking this step. Has anyone else been through something like this.