Narrator: This is Science Today. For many expectant parents, having a prenatal ultrasound means getting an exciting first peek at their baby, but as a diagnostic test, ultrasounds are extremely important for predicting birth outcomes and risks. Rebecca Smith-Bindman, a researcher at the University of California, San Francisco, explains.

Smith-Bindman: I think patients have started to look at ultrasound in a way that it's just a fun test that they have to see a picture of their baby and I'm very sympathetic with that view of ultrasound. But it's really a medical test and really has a very important medical role for predicting who's really at greatest risk.

Narrator: Smith-Bindman suggests getting an ultrasound as early as 15 weeks gestation, instead of the routinely recommended 20 weeks, so that babies in highest-risk groups can be identified earlier.

Smith-Bindman: If we could identify those fetuses who are greatest risk, we can then have more success in trying to develop interventions that can help them.

Narrator: For Science Today, I'm Larissa Branin.