There is nothing quite like the tingle of anticipation before you “see” your baby for the first time. For many expectant mothers, this happens during the first few months of pregnancy by means of a pregnancy ultrasound.

Here’s everything you need to know about ultrasound during pregnancy.

What is ultrasound and how does it work?

An ultrasound scan uses sound waves to create an image (called a sonogram) of your baby. This scan also shows the uterus, placenta, blood vessels, and surrounding organs. A special kind of ultrasound known as doppler ultrasound is used to check your baby’s blood flow, as well as the blood flow in your uterus and placenta.

When will I have my first pregnancy ultrasound?

Some women don’t have their first ultrasound until the second trimester, but many will have an ultrasound during the first 6-10 weeks of their pregnancy. A doctor may perform an early ultrasound when a pregnancy is considered high risk, when a previous pregnancy has been complicated, or when there have previously been congenital disabilities.

Pregnancy ultrasound schedule (week by week)

Your doctor may have their own preferences for the timing of your scans, but you will usually have between 1 and 4 ultrasounds during your pregnancy. Depending on your risk profile, you can expect to have some or all of the following scans:

Early pregnancy ultrasound (6-8 weeks)

The purpose of an early ultrasound is usually to confirm a pregnancy.

The doctor or sonographer (ultrasound technician) will also:

• check for signs of an ectopic, or tubal, pregnancy (fetus growing in the fallopian tube rather than the uterus)
• determine the number of fetuses you’re carrying
• provide accurate gestational dating by crown-rump length
• determine your estimated due date (EDD)
• check your baby’s heartbeat (detected from about 6 weeks)

A gestational sac is usually visible as early as 4 ½ weeks after the first day of your last period.

In the early stages of pregnancy, the ultrasound might be performed transvaginally (internally) as this provides a clearer picture of your baby. If a transabdominal (belly) ultrasound is used, you may be asked to drink several glasses of water before the procedure as a full bladder helps produce a clearer image.

A condition known as a molar pregnancy is another thing doctors check for. In this instance, the placenta doesn’t develop as it should. Instead, it forms a cluster of blood vessels and tissue. The scan will reveal a cyst-type growth in the uterus. This kind of pregnancy is usually not viable because the placenta is unable to nourish a growing baby.

Dating ultrasound (10-13 weeks)

If you didn’t have an early pregnancy ultrasound, you may have a “dating ultrasound” at between 10 and 13 weeks. This scan provides similar information, including:

• Estimated due date (EDD)
• Crown-rump length (measurement from head to bottom)
• Number of fetuses
• Fetal heartbeat

The American College of Obstetricians and Gynecologists (ACOG) provides the recommendations for determining estimated gestational age and due date. This information is important for early prenatal care. Scans performed before 12 weeks are the most accurate in determining EDD.

Nuchal translucency ultrasound (14-20 weeks)

If your screens identify a potential problem, you have a family history of birth defects, or you are over 35 years of age, you should consider a nuchal translucency test (NT). For this test, your doctor uses ultrasound to estimate the thickness at the back of your baby’s neck. A thicker neck may indicate conditions such as trisomy 18 and Down Syndrome.

Anatomy scan/screen (18-20 weeks)

What is an anatomy scan? It is the detailed ultrasound we are familiar with from TV shows and movies. By this time, your baby is well developed, and the doctor or sonographer will use this scan to check for any abnormalities in the baby’s heart, brain, liver, kidneys, and lungs.

They will also count fingers and toes, measure how much amniotic fluid you have, and check the placenta. During this comprehensive examination, they should also be able to determine your baby’s sex, if you want this kept a surprise, make sure you let them know in advance.

Third trimester ultrasound

A third trimester ultrasound is not necessary during a healthy pregnancy. Your doctor may decide to perform a quick check-up during your antenatal appointment to reassure you that everything is fine. They may also scan during this last trimester if your pregnancy is considered high risk, or if you have experienced any complications such as bleeding, preterm contractions, or a low level of amniotic fluid.

Additional reasons for ultrasound

Apart from the scans mentioned above, ultrasound can be used with other prenatal tests or at other times during your pregnancy. Some examples of other reasons for an ultrasound scan include:

• For a chorionic villus sampling procedure: This sampling is used to get an early diagnosis of genetic or chromosomal abnormalities. It usually takes place between 10 and 12 weeks after your last period.
• During amniocentesis: This procedure uses a needle to remove some amniotic fluid to test for chromosomal abnormalities and infections. It will also reveal the sex of the fetus. This procedure may be recommended if you are over 35, have a family history of a genetic condition, or you or your partner are known carriers of a genetic condition.
• If bleeding or any other concerns develop: Ultrasound can be used at any time to check blood flow, volume of amniotic fluid, and the health of the placenta.

If you have a family history of any inherited conditions, you might also be asked to consider other genetic testing during or even before your pregnancy.

Types of pregnancy ultrasounds

Pregnancy ultrasounds take place either abdominally or transvaginally. While your doctor usually uses ultrasound to check the health of your developing baby, they may also use a pelvic ultrasound to check your cervix.

• At your check-ups, ultrasounds are usually two-dimensional and provide the familiar black and white images.
• A 3D ultrasound takes thousands of pictures at a time to create a clear three-dimensional image. This type of scan can be used to check organ growth, look for abnormalities in a baby’s face, and identify any uterine problems.
• A 4D ultrasound is similar to the 3D ultrasound, but it is compiled into a video clip that shows movement.

The best time to have a 3D or 4D scan is between 27 and 32 weeks, when the baby has accumulated some fat under their skin, but before things get too crowded.

Preparing for your pregnancy ultrasound

Fortunately, an ultrasound scan doesn’t require much preparation. About an hour before an early pregnancy ultrasound, you may be asked to drink some water. A full bladder helps the sound waves produce better pictures.

As the amount of amniotic fluid increases, this will no longer be necessary. Consider wearing a two-piece outfit to make access to your abdomen easier. You can eat normally before your ultrasound as this won’t interfere with the procedure in any way.

How many ultrasounds are safe during pregnancy?

Ultrasounds are extremely low-risk procedures when performed by a properly qualified doctor or sonographer. While there is no hard-and-fast rule, the ACOG recommends having only one or two ultrasounds in total unless more are medically required.

Current research indicates that ultrasounds are safe for developing babies, and to date, no links have been found between ultrasound and birth defects, cancer, or developmental issues. However, it’s still recommended that ultrasound should only be used when necessary and performed by a qualified professional.

How much does an ultrasound cost?

An ultrasound performed by licensed and qualified doctors or sonographers can cost anywhere between $100 and $1,000. If you have medical insurance, your carrier will cover some or all of the cost in case the procedure is medically necessary. Not all insurance companies cover 3D scans, so always contact them in advance if possible.

There are many benefits to having an ultrasound, including the peace of mind of knowing that any problems would be identified early. For me, by far the biggest benefit was the gift of seeing my unborn child. Being able to see my baby moving and growing was the beginning of my bonding process, and having that picture in my mind made it far easier to stay positive and focused during the challenging parts of each of my pregnancies.