The sheer number of prenatal tests can be overwhelming and confusing for many first-time moms-to-be. An amnio-what? Is the non-stress test for you or the baby? And what the heck is an alfa-fetoprotein screening? Experts answer these questions and more to put expecting moms' minds at ease.

Fetal monitoring is a method of listening to the growing fetus' heart tones (or heartbeat) using a monitor on the mother's belly, says Dr. Aneema Van Groenou, a physician and author of The Active Woman's Guide to Pregnancy: Practical Advice for Getting Outdoors When Expecting (Ten Speed Press, 2004). "Most Doppler devices at doctors' offices can pick up the baby's heart by the end of the first trimester. This exam simply involves putting some gel and a probe on top of the mother's belly and listening for the fetal heart. The probe uses ultrasound to detect the heart and is not harmful to the fetus at any gestational age. However, the earlier the pregnancy and the more the fetus moves around, the harder it is to pick up the heartbeat."

Dr. Van Groenou says you will hear the gallup of the fetus' heart, and the doctor will count the beats per minute to make sure they are in the healthy range. "But be prepared, because hearing your little one's heart for the first time can be pretty emotional," she says.

The literal answer to your question is that you have no way of knowing if the baby is in "distress," says Dr. Michael Benson, attending physician at Highland Park Hospital in Illinois. "There are no symptoms. In theory, fetal monitoring can detect babies that are not receiving enough oxygen during labor," he says.

Dr. Benson says there are three caveats to this idea:

1. In the 1960s it was believed that most cases of cerebral palsy and mental retardation resulted from lack of oxygen during labor. We now know that the opposite is true: fetal injury rarely occurs during labor. Most of these neurological injuries result from problems (some recognized and most not) from before the onset of labor.

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