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Pregnancy Health Center

9 Month Miracle ##RemoveMe##
Welcome to Week 18
18 Week Old Fetus
Your Baby: Did You Hear a Hiccup?

At about 5 1/2 inches (14 cm) in length and up to 7 ounces (200 g) in weight, the fetus is growing fast and looking more and more babyish. During this week, your baby's sense of hearing has become much more acute. The baby can hear noises within the uterus of your bowel moving and even the blood pumping within your vessels. Your baby can also hear things outside the uterus. So if you are talking to your partner, the baby is hearing some sound. (You may even feel the baby hiccup and get startled from noises that take place outside!)

Your Body: Having an Ultrasound

If you're like most women, you'll have a routine ultrasound about now so your caregiver can get information on your baby's health. Though this brief (5 to 10 minutes) and painless test is most often done during the second trimester, it can be performed any time between the fifth week of gestation and delivery.

There are two types of ultrasounds: transvaginal and transabdominal. With both, you lie on your back on an exam table while your belly or a probe is lubed with a special gel. A transducer (a small microphone-like device) is gently pressed on your belly or inserted into your vagina. The method used depends on how far along you are and what type of equipment is on hand. The transabdominal transducer is moved over your belly. It works by sending out high-frequency sound waves and then picking up the sound waves that bounce back off the bones and tissues in the body. These sound waves then produce an image on a nearby computer screen. The image on the screen, which for some is crystal clear and for others a big blur, is your baby. Regardless, most expectant moms find this first glimpse thrilling -- and over all too quickly.

Ultrasound is a non-invasive test that provides a tremendous amount of information to your health care provider about your baby's development and health. Some of the things that can be seen by ultrasound include:

  • Determine an accurate gestational age of the baby
  • Determine sex of the baby
  • See any anatomical abnormalities that exist in the baby
  • Determine if it is just one baby or more than one
  • See the location of the placenta and the baby's position within the uterus
  • See the amount of amniotic fluid
  • Watch how the baby's heart is beating
On That Note: Baby on View

As your next -- or in some cases, your only -- ultrasound draws near, you're eager to get a look at the precious cargo you're carrying. For a sneak preview of what the test entails, take a look at this ultrasound presentation.

Weekly Tip

Wear loose-fitting separates for the ultrasound exam. That way, you can easily pull the top half up and the bottom half down. And even though you'll mop up the goop on your belly with a towel when it's all over, some of it will surely wind up on your clothes. So whatever you do, don't wear your Sunday best!


Review Date: 7/8/2017

Reviewed By: John D. Jacobson, MD, Professor of Obstetrics and Gynecology, Loma Linda University School of Medicine, Loma Linda Center for Fertility, Loma Linda, CA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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