What Happens During an Ultrasound?

What is an ultrasound, when does it happen and what does it test for? Your questions, answered.
ByPaula Kashtan
Apr 2017
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Ultrasound uses sound waves and echoes to create a moving image of your fetus and show what’s going on inside your womb. (Quick vocab lesson: Ultrasound is the procedure; sonogram is the image it creates.)

Some doctors routinely perform first trimester ultrasounds between weeks 4 and 12 to confirm the fetus’ age. Or, your doctor might perform one in the first trimester only if there are signs of multiples, miscarriage or ectopic or molar pregnancy. Between weeks 18 and 22, most women have a more detailed level two ultrasound. Now, your doctor is checking for fetal heartbeat, location, breathing, movement and size, placenta location, amount of amniotic fluid, abnormalities and yes, gender. Look forward to the fuzzy picture you’ll get to take home as a souvenir of baby’s first photo session. Throughout your pregnancy, your doctor might order additional ultrasounds to check on any issues or possible complications—for example, if you experience bleeding or pelvic pain, ultrasound may be used to help find the cause.

Rest assured that ultrasound is safe for you and baby—of the multitude of large studies performed over the last 30 years, none have linked ultrasound to any harmful effects, for you or your child.

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