7 scans and tests that pregnant mothers should have in their third trimester

Pregnant mothers who are in their third trimester should have the recommended scans and tests provided by their doctors.

During your prenatal visits in the third trimester,  you will have to undergo weight and blood pressure checks for scans and tests. Your doctor or midwife will measure the size of your uterus (fundal height) and feel your belly. This is for checking your baby’s growth and position.

Later in the third trimester, your doctor or midwife will check to see how your baby’s head drops nearer to your pelvis. If your baby is not head-down after 36 weeks, you may have a fetal ultrasound to confirm your baby’s position.

With this, your care provider may try an approach to gently move the baby into a head-down position. Drawing closer to your delivery, you may be checked to see if your cervix has begun to thin and open.

In this article, we will be talking about the scans and tests that you should have during your third trimester. You may be advised to undergo all tests, or it will depend on your pregnancy and your condition.

Third trimester scans and tests

Throughout your pregnancy, you will want to know how your baby is growing. Prenatal tests and scans can offer valuable information about your health and your baby during the third trimester.

If your doctor recommends a scan or test, make sure that you will learn about the risks and benefits. Most mommies find that prenatal checkups offer them peace of mind while in preparation for their baby’s arrival. But, it will be always your choice to accept or decline a test.

7 common scans and tests during your third trimester

During the last trimester of pregnancy, your doctor may suggest that you have certain diagnostic tests. These 7 recommended tests are all safe and will ensure the optimized welfare of both the mother and baby.

The following are some of the most common tests pregnant mommies should have:

1. Group B Streptococcus  screening

Group B Strep (GBS) is a type of bacteria that exists in the female reproductive tract without causing symptoms. An estimated 30% of healthy women may carry GBS, and usually, it does not cause any health problems.

However, sometimes it might lead to a serious infection in the bloodstream, infection of the placenta, or urinary tract infection. Group B Strep can also have serious consequences for the baby, causing potentially life-threatening infections in the newborn. These infections might include meningitis, pneumonia, and sepsis.

Testing is simple and may involve taking a sample from the vagina and from the rectum using a cotton swab. The swab to be used is cultured in the laboratory to see if GBS is present.

If the result is positive, your doctor may give you antibiotics during labor to reduce the risks of infection in the baby. The test is usually done between the 35th and 37th weeks of pregnancy.

2. Electronic fetal heart rate monitoring

Electronic fetal heart rate monitoring is usually for confirming if the baby is healthy. This type of monitoring is also needed during labor and delivery. You might have this monitoring after the 2oth week of gestation while having your prenatal checkups.

3. The non-stress test (NST)

The non-stress test or NST involves a fetal monitor strapped to your abdomen to quantify the baby’s heart rate as it moves. This test is called non-stress because literally, no stress is placed on the baby for the test.

Additionally, this test is performed on a weekly basis in high-risk pregnancies. It is administered after the 28th week of pregnancy, though most commonly after 32 weeks. Usually, a doctor may take measurements of your baby’s heart rate for 20 to 30 minutes.

Furthermore, an NST may be recommended if you feel the baby moves oddly or is not normal. This is recommended by the doctor if you are past the due date, or if the doctor wants to ensure the placenta is healthy and functioning well.

There are no known issues with the NST for both the mother and baby.

4. A biophysical profile

A biophysical profile (BPP) synthesizes the information from an NST with an ultrasound scan of the baby for a more precise evaluation.

5. A contraction stress test

A contraction stress test or CST, like the NST, quantifies the fetal heart rate. However, in this test, your baby’s heart rate is measured in response to uterine contractions that are extracted through giving oxytocin or by stimulation of the nipples.

The test is sometimes called as oxytocin challenge test.

6. Third-trimester Ultrasound scans

An ultrasound is a safe and painless test that uses sound waves in making images that show your baby’s shape and position in the uterus.

An ultrasound scan may be performed in the third trimester if needed to aid in evaluating your baby’s growth and look for problems with the placenta. Sometimes, it may be a part of BPP to see whether your baby is getting enough oxygen.

Mothers with results in tests of high-risk pregnancies might have multiple ultrasound scans in their third trimester.

7. Third-trimester blood tests

Certain lab scans and tests are part of routine care during pregnancy, from the first to the third trimester. Some of these tests are done with blood samples. The third-trimester blood tests during pregnancy may help find conditions to avoid higher risks of any complications.

What blood tests are done during pregnancy?

Your first visit to a doctor or obstetrician should have included a full physical, urine (pee) test, and blood test to check for any condition. These tests will check things like:

• your blood type and Rhesus factor (Rh). If your blood is Rh negative and your husband is positive, you might develop antibodies that are dangerous to your baby. This can be prevented with an injection for pregnant mothers in their 28th week of pregnancy.
• anemia, a low red blood cells count.
• hepatitis B, syphilis, and HIV
• immunity to rubella (German measles) and varicella (chickenpox)
• cystic fibrosis and spinal muscular atrophy. Health care providers now routinely offer to scan for these disorders even when there is no family history.

You may also expect to get your urine tested and your weight and blood pressure checked at every visit until your delivery. These tests can point out conditions such as gestational diabetes and preeclampsia (dangerously high blood pressure).

Third trimester ultrasound scans

Not all pregnant mothers might need a third trimester ultrasound scans. Some of the reasons why a third trimester ultrasound may be required for some mommies are the following:

• If medically the baby may feel larger or smaller than expected during the gestation
• When the mother has a medical condition that could influence the baby’s growth and well-being
• If the placenta was low-lying on the mid-trimester ultrasound
• When a doctor is unsure of the baby’s fetal head position
• If there is a pain in bleeding
• When the fetus is not moving well
• If a fetal abnormality was noted on an earlier ultrasound

Many obstetricians refer pregnant mothers for two (2) third trimester ultrasounds. They might request to do it within 28-36 weeks because there is increasing proof that third trimester ultrasound allows better detection of growth.

On a third trimester ultrasound, we always need to remember:

• Fetal anatomy, although late in pregnancy, the views of the baby’s parts may be difficult to see.
• fetal position
• placental position
• fetal size
• baby’s welfare
• The blood flow in the umbilical cord gives an idea of placental function.

So mommies, prepare for these scans and tests that will be recommended in your third trimester. Always ask and consult with your doctor if a test is good for you and your baby’s health.

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