An ultrasound, also referred to as sonogram, is a test that uses high frequency sound waves to produce pictures of the pregnant woman's reproductive organs to exam the health of the fetus. Every pregnancy requires different number of ultrasounds and an ultrasound should be done only when suggested by your doctor. A sonogram helps detect problems if any and helps monitor the normal growth and development of the fetus. Ultrasounds can be of different types like a standard ultrasound, a 3D ultrasound or a 4D ultrasound which is more advanced. At times, an echocardiography of the fetus is conducted which helps look at the heart of the fetus.

When and Why to Have an Ultrasound During Pregnancy

1. First Trimester

• An early scan at 6 or 7 weeks is carried out only if there is a complaint of pain or vaginal bleeding.
• Normally, your first scan, also referred to as the dating scan, is done any time between 11 weeks and 13 weeks plus 6 days of pregnancy, which is used to confirm the date of your pregnancy. This scan is important if you want to screen your fetus for Down's syndrome because exact due date is needed to get accurate results.
• A nuchal translucency (NT) scan along with blood tests can be conducted between 11 weeks plus 2 days and 14 weeks plus1 day of your pregnancy or when your fetus measures between 45 mm and 84 mm.

2. Second Trimester

An anomaly scan is done at about 20 weeks of pregnancy to check if the fetus is growing normally. This scan may be repeated at 23 weeks of pregnancy if your doctor can't get all the needed information to assess your baby's health. This could happen if the expectant mom is overweight or if the baby is not in the right position.

3. Third Trimester

During third trimester, your doctor will recommend an ultrasound anytime between 28 – 40 weeks of your pregnancy. This is done because:

• The growth of the fetus has to be checked regularly.
• The mother has previously given birth to a smaller baby.
• The mother has medical conditions like diabetes or high blood pressure.
• The mother is having twins.
• The fetus is smaller or larger than it is supposed to be.
• The doctor or midwife suspects that there is too much of fluid surrounding the baby.

Watch the video blow to know how to do ultrasound in pregnancy, what to check and how to read the image of ultrasound, etc. 

Is Ultrasound During Pregnancy Safe?

Research that has been conducted over last 35 years does not prove that an ultrasound done during pregnancy can harm the developing fetus since the ultrasound does not involve radiation. But the research also suggests that ultrasounds should not be done unnecessarily as they are some form of energy and may harm the developing baby especially during the first trimester.

What If the Result Is Abnormal?

If the results of an ultrasound during pregnancy are normal, the developing fetus, placenta, amniotic fluid and surrounding structure will appear normal for the gestational age. If the results are abnormal, consult your doctor and have a detailed discussion about it.

• First, do not panic and be calm when discussing with your doctor. Follow-up tests are often conducted to cross-check the results and it may not turn out to be that serious after all.
• Second, the results from the ultrasound scan help your doctor design and follow the best course of treatment. For example, if serious heart rhythm problems are detected, chances are that they can be treated with proper medication while the fetus is still in the womb. Urinary tract blockage can be treated with operation before the birth of the child.
• Last, with severe birth defects, getting all the information ahead makes it easier for your doctor to decide on the right line of treatment and care. For example, to decide whether the pregnancy should be medically terminated or how to prepare for the birth of the baby who will need extra special care. Ask a genetic counselor any question you may have.

3 More FAQs About Ultrasound During Pregnancy

When you are pregnant, especially if it is your first baby, a lot of questions will build up in your mind. Here are a few FAQs to help you:

When Can an Ultrasound Determine the Sex of the Baby?

An ultrasound carried out between the periods of 18 to 20 weeks can help determine the sex of your baby and other complications, if any. Several factors like the stage of pregnancy and position of the fetus contribute to the accuracy of the results.

How to Prepare for an Ultrasound During Pregnancy

There is no special preparation to be done for an ultrasound. You will only be asked to drink 4 to 6 glasses of water and will not be allowed to urinate until the test is completed. Keeping your bladder full before conducting the scan can give your doctor a better view of the fetus. Ask your doctor if you can video tape the ultrasound on a CD or a DVD. If the doctor says yes, take an empty CD or DVD with you to record it.

Will I Feel Pain During an Ultrasound?

Generally, an abdominal scan does not inflict any pain but there might be times when you may experience a little discomfort when the transducer is pressed against your abdomen or if your bladder is very full. In case you feel discomfort, tell your doctor who might ask you to empty half your bladder after which you may not feel the discomfort.