It's peace of mind for thousands of expectant parents: A new technology gives doctors a four-dimensional view into the womb weeks before a baby is born.

Sladja Stantic, 27, is having a baby for the first time.

"When I first found out I was very excited more than that," said Stantic.

Now just weeks away from delivery, she knows she's having a girl and naming her Emma. But she also knows exactly what Emma will look like right down to her toes thanks to a new 3D-4D ultrasound.

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"When you actually see the baby, you see the baby's face. Like the last time, I saw the baby's nails, the toenails. It's unbelievable," said Stantic.

The new 3D-4D ultrasound takes three-dimensional images, but then adds the element of time, allowing doctors to visualize the external and internal anatomy with almost picture-perfect detail.

"It allows us to get deeper studies of the inside anatomy. As a physician we want to know if there is a problem with an internal organ," said Dr Cesare Di Rocco.

And since this new device can diagnose everything from cleft lips to congenital heart defects, it is a clear advantage over the traditional two-dimensional images.

"This is cutting-edge state of the art medicine, and I think in this day and age you should practice state of the art cutting edge medicine," said Di Rocco.

But for Sladja, who will soon greet Emma's familiar face, it's about reassurance.

"For me it's comforted me so much. It's really been unbelievably helpful to me."

The 3D-4D ultrasound is only available at a few locations nationwide.

It's so new that many health insurance companies are just catching up in covering the test.