You have just left the doctor’s office with the precious images of your baby’s ultrasound in hand and you just can’t wait to show them off. Only when you start to pass the images around to family and friends, you have to keep explaining that the little white blob on the black background is, in fact, your baby, and not a rorshock test.

Now imagine the same scenario, only this time you have a crystal clear image of the cutest little scrunched up baby face in hand. Your friends and family are in awe at the little face staring back at them.

What’s the difference?

The first example is what you get with the traditional 2-dimensional ultrasound most women receive when they are about 18 to 20 weeks pregnant. And the second is the image you may be lucky enough to capture with the help of a 3- or 4-dimensional ultrasound.

Heid Zook is the mother of two—Brigitte, 2 years, and Gretchen, 4 months. The Roseville, MI, resident had a 3-D ultrasound with her youngest.

“It was cool,” she said of the little snapshot of Gretchen. “It was bizarre at first. You could see her little eyes and her little nose and her chubby cheeks.”

Zook had the ultrasound done near the end of her pregnancy at the recommendation of her doctor.

“They did the ultrasound originally to check the level of amniotic fluid around the baby to make sure she was okay because I was measuring three weeks ahead of my due date,” Zook said. “Once they knew that everything was okay, the technician said she was going to ‘try something’.”

Ultrasounds are commonly performed during pregnancy at the request of doctors for a variety of reasons such as determining the baby’s size and finding out how many babies a mother may be carrying. The ultrasound also can be used as a tool to evaluate the baby’s heart rate, movement, and to detect birth defects.

During the procedure, a small transducer is placed on a mother’s abdomen, which then sends sound waves into the body. The sound waves are then bounced back, reflected off of the mother’s internal structures and the baby’s as well.

The transducer then translates the reflection into a picture on the screen. But the image itself is more like a one-dimensional slice that is sometimes hard to translate, says Clark Nugent, Professor of Obstetrics and Gynecology in the Division of Maternal Fetal Medicine at the University of Michigan.

When it comes to 3- and 4-D imaging, the difference between the two can be likened to a still photograph and a video. Says Nugent, 3-D is the still shot taken from the real-time 4-dimensional image viewable on the ultrasound screen.

Laura Reed of Plymouth, MI, is also the mother of two—two-and-half-year-old David, and three-month-old Joseph. While she chose to have a 4-D ultrasound performed when she was pregnant with Joseph, she skipped that option when pregnant with David due in part to cost.

“I just thought it would be fun for the scrapbook,” Reed said, who had the procedure performed at her obstetrician’s office. Her fee of about $60 included a keepsake DVD.

“It was a little disappointing because he was asleep, but it was nice to get to see him. The added, ‘He’s Okay,’ was nice, too.”

But the ultrasound that is being offered by keepsake facilities is not something that Nugent recommends, unless it is medically necessary. Its purpose, he said, is to help physicians and properly trained technicians analyze fetal development.

And Nugent isn’t the only one who believes women should forgo the procedure unless prescribed by a doctor.

According to the Food and Drug Administration (FDA), the long-term effects of repeated ultrasound exposure on the fetus are not fully known. When having the procedure performed by a trained sonographer or obstetrician to determine fetal movement, birth defects, and other factors such as number of fetuses, the medical benefit outweighs possible risks. But studies have shown that the energy produced by ultrasound can produce physical effects, like internal vibrations and a rise in temperature. There is no evidence to suggest that this can harm a fetus, but the fact that there are any effects at all only add to the “for medical use only” directive.

Either way, there is a specific window of opportunity for both traditional and 3- and 4-D ultrasounds.

“If a woman is planning on getting one ultrasound to verify gestational age and check for possible birth defects, the recommendation is between 18 and 20 weeks of pregnancy,” Nugent said. “But recreational ultrasounds performed for non-medical reasons are discouraged. This is a medical device.”

Nugent says that proper training is the key when it comes to using and translating the information received via the transducer.

“A keepsake ultrasound does not take the place of a diagnostic study,” Nugent says.

But will 3-D imaging ever replace 2-D imaging as the standard in doctor’s offices?

Studies are currently being performed to determine if there is scientific superiority of 3-D scanning over the 2-D images routinely used today. Issues such as identifying facial abnormalities and neurological and cardiac abnormalities are being looked at with these studies, Nugent says.

“And, from the parents’ perspective, the 3- and 4-D images are easier to interpret compared to two dimensional images,” he says.

Some medical centers are transitioning to 3-D imaging, Nugent says. But time will tell how the technology is ultimately implemented.

Whether an image is made for medical or personal reasons, the baby has to participate if the person performing the ultrasound is to gather the information they may be seeking.

“Like toddlers, not all babies are willing to pose for you,” says Nugent. “In order to get a good 3-D image, the baby cannot be against the wall of the uterus nor have a hand in front of its face, or the images can bleed into each other.”

The bottom line? Even technology is no match for the squirmiest and smallest of babies.

For Roseville-mom Zook, her ultrasound experience helped her medical providers determine that she needed to have a cesarean section performed two weeks before her expected due date. At the time, she had three weeks left to go, and her 4-foot-11 frame was being stretched to the maximum with her baby’s 7.8 lb measurement.

One week later, little Gretchen Marie was born, weighing in at 8.6 lb.

“I think it takes the excitement out if it, especially if you find out the sex,” Zook said of the ultrasound. “I mean, it was cool to see her face, but once I knew she was okay, that was all I needed to know.”