This is perhaps the one test during a pregnancy that both father and mother look forward to, because it gives them their first glimpse of their new child. In an ultrasound test, a lubricating jelly is applied to a woman's abdominal area and an ultrasound "wand" is guided across the surface of the skin. High-frequency sound waves are transmitted into the uterus and bounce back to return an image of the fetus.
Although parents will remember the test as the first time they got to see their baby's heartbeat or find out the child's sex, doctors conduct fetal ultrasounds for other reasons as well. The test is useful for discovering the gestational age of the baby which helps plan pre-natal care and predict a delivery date. It also helps locate the fetus and make sure that it is properly situated in the uterus, not in the fallopian tubes, which would indicate a dangerous condition known as an ectopic pregnancy. Fetal ultrasounds additionally make sure the baby is growing correctly and help identify any fetal abnormalities, examine the placenta to make sure it is healthy, and let expecting parents know if they're only having one child or multiple births.
Fetal ultrasounds are typically conducted in the first trimester of the pregnancy and then again about midway through, but they can be used more than that if need be, as they are a very safe testing mechanism.