That initial glimpse at your baby-to-be is unforgettable. Here’s what to expect at your first pregnancy ultrasound.

Getting that initial glimpse of your baby on an ultrasound machine is one of the most exciting moments of pregnancy. Yet many parents-to-be are filled with questions about the first pregnancy ultrasound: When should I get the exam? Will it hurt? What are doctors looking for? We spoke with experts to break down your most pressing questions.

What is an Ultrasound?

An ultrasound is a painless diagnostic test that most women will receive during pregnancy. High-frequency sound waves travel into your uterus, and they bounce back from the fetus as vibrations. The echoes are translated into electrical signals that are projected as black-and-white pictures on a monitor. The images display your baby's soft tissues and organs.

What Should I Expect at My First Pregnancy Ultrasound?

An ultrasound usually can be done in your practitioner's office or your local hospital. There are two types: transvaginal probe and transabdominal ultrasound.

Transvaginal Probe: If you need an ultrasound early in pregnancy, it may be necessary to use a transvaginal probe (a transducer placed in the vagina). The fetus is deep in the mother's pelvis in early pregnancy—and since sound waves don't pass through bone, a transvaginal ultrasound lets your technologist to view your uterus through the cervix. This method may also be used later in pregnancy to locate your placenta if it's over the cervix or to measure the length of the cervix. 

A transvaginal ultrasound is done with a wand-shaped probe covered with a latex sheath (like a condom). The doctor will apply some lubricant and gently insert the ultrasound into your vagina. She will move the device to form the picture she needs on the ultrasound screen. The procedure doesn't hurt, but you might find it uncomfortable in the same way you might find a pelvic exam uncomfortable. 

Next the doctor moves the transducer along your abdomen, applying some gentle pressure. The transducer transmits sound waves that create a picture of the baby inside. If you're ticklish, you might find yourself challenged during this procedure. Take a deep breath and try to relax!

When Do You Get Your First Ultrasound?

Wondering when is the first ultrasound? The answer varies for everyone. 

Early Pregnancy Ultrasound (6-8 Weeks)

Some doctors perform the first ultrasound exam around 6 to 8 weeks of pregnancy, often during the first prenatal visit. Others only recommend this exam if a woman has symptoms of a high-risk pregnancy—for example, bleeding, abdominal pain, or a history of miscarriage, birth defects, or pregnancy complications

During this time, your baby is very small and your uterus and fallopian tubes are closer to your birth canal than to your abdomen, so your OB-GYN might conduct the test transvaginally to get a clearer picture.  

Your OB-GYN first listens for your baby's heartbeat. From this test, your doctor will be able to determine a more accurate due date and track milestones during your pregnancy. She'll also be able to tell if you're pregnant with multiples, and she'll determine if you have an ectopic pregnancy. This is when the fetus grows in the fallopian tube instead of the uterus. (Don't worry: Ectopic pregnancy occurs only 1 percent of the time.) 

Dating Ultrasound (10-13 Weeks)

What's more, your OB-GYN will examine the basic anatomy of your fetus. One of the most common early pregnancy measurements is crown-rump length, which measures your baby's size from head to tush. The reason it's important? "This measurement is extremely accurate in dating the pregnancy in the first trimester," says Michele Hakakha, M.D., an OB-GYN in Beverly Hills and author of Expecting 411. "It helps us determine if the size of the fetus matches up with the size it should be based on the patient's last menstrual period." If this number is considered off early on, that could indicate potential issues. "A smaller crown-rump length may signal an embryo that is not developing normally and may have a chromosomal problem, or it could mean that a woman's dates are off and she is not as far along as she thinks."

At the same time as your dating ultrasound, pregnant women are offered a nuchal translucency (NT) test, which evaluates your risk of having a baby with Down syndrome, other chromosomal abnormalities, or certain heart defects. In this two-part exam, a blood test measures levels of certain hormones and proteins in your body, and an ultrasound determines the thickness at the back of the baby's neck (increased thickness indicates that he may be at risk for birth defects such as Down syndrome and trisomy 18). 

Anatomical Survey (Weeks 18-20)

If you don't have a first trimester pregnancy screening, your first ultrasound will typically be done between 18 and 20 weeks. "We look at about 35 elements, including the brain, heart, kidneys, limbs, face, gender and more," says Jane Chueh, M.D., director of prenatal diagnosis and therapy at Lucile Children's Hospital Stanford, in Palo Alto, California. Your baby will also have measurements taken of the diameter and circumference of her head, the circumference of her abdomen, and the length of her femur bone.

The examiner is looking for physical characteristics that might indicate any abnormality. Ultrasounds can't detect all birth defects, and a normal ultrasound doesn't guarantee a healthy baby. However, ultrasound is a wonderful diagnostic tool that can help ensure that your pregnancy and your baby are both on the right track.

How Do You Prepare for an Ultrasound?

After you make your appointment, your doctor will give you an instruction sheet telling you what you need to do. Generally, women who are less than 14 weeks pregnant will be asked to fill their bladder to capacity. Sound waves travel better through liquid, so a full bladder improves the quality of an ultrasound during early pregnancy. As a woman's pregnancy progresses, a full bladder is not as essential because the uterus and fetus are so large. But even then, some physicians ask their patients to come with a full bladder because transmission of the sound waves is better with fluid in the bladder.

Here are other tips for your first ultrasound:

  • Wear two-piece clothing to your ultrasound, to allow for easy access to your tummy.
  • At some high-tech centers, doctors use 3-D ultrasound to provide pictures of the baby with photograph-quality details. High-tech centers may use this type of ultrasound to better evaluate a baby's growth and development, as well as detect facial abnormalities or neural tube defects. If you have certain pregnancy complications, this type of exam may be recommended.

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