Your Pregnancy | Second Trimester Tests and Screenings

Second Trimester Tests and Screenings

When you reach week 13 of your pregnancy, you’re officially in your second trimester. Many exciting changes happen during the second trimester — the not-so-fun pregnancy symptoms are likely to subside and you’ll start to see and feel your baby growing and moving in your belly!

Because of these changes, you’ll have to make a few visits to your doctor to make sure your baby is developing healthily and that your body is handling pregnancy as it’s supposed to.

Your doctor will likely recommend seeing you for appointments every four weeks during your second trimester, but because of certain COVID-19 restrictions, your visits might be reduced.  Your doctor might use telehealth services to check up on you and your baby instead.

During your appointments, there are a few standard tests and screenings your doctor will run to monitor the growth and health of you and your baby.

Glucose Screening and Tolerance Test

By your second trimester, you should be no stranger to a good old-fashioned blood test. You will have had one at your very first prenatal appointment so that your doctor could learn a few things about you and your pregnancy.

In your second trimester, however, you’ll have to get more blood drawn to check for gestational diabetes. According to the Centers for Disease Control, gestational diabetes affects between 6 and 9 percent of pregnant women. If treated properly, it shouldn’t prevent you from having a healthy and successful pregnancy.

For the glucose test, your doctor will have you drink a sugary drink and then wait about an hour before drawing your blood. If your blood work shows high levels of glucose — 190 milligrams per deciliter — your doctor will want to do a glucose tolerance test.

A glucose tolerance test is similar to the initial glucose test, except this time the glucose drink will be even sweeter, and your blood will be drawn every hour for three hours. If two or more of the readings from your blood work are higher in glucose than normal, you’ll receive a gestational diabetes diagnosis.

Treatment for gestational diabetes typically includes

  • Healthy diet and exercise
  • Blood sugar monitoring
  • Medication, if necessary

Most women who are diagnosed with gestational diabetes will see their glucose levels return to normal after they have their babies. But it’s still possible to develop type 2 diabetes. You’ll have to have your diabetes risk assessed every two to three years after delivery to keep an eye on things.

20-week Anatomy Scan

The most exciting screening for many expecting mothers is the ultrasound. You’ll already have had one in the first trimester, and around week 20 of your pregnancy, you’ll get to have your level two ultrasound, also known as the 20-week anatomy scan.

Because your baby has grown so much since the first ultrasound, there is so much to see and learn about her at the 20-week scan! During this ultrasound, the sonographer can measure your baby, check on your amniotic fluid levels, identify the location of the placenta and survey the heart, bladder, stomach, brain, spine, and genitalia of your baby. Make sure you tell your doctor if you want the sex of your baby to be a surprise!

The level 2 ultrasound is extremely important because it helps your doctor see more clearly any abnormalities your baby might have. The detection rate for birth defects with the level 2 ultrasound is about 70 percent. Learning about a potential birth defect at the 20-week mark can prepare you and your doctor for whatever treatment your newborn might need or prevent serious complications during and after delivery.

Here are some tips to prepare for your 20-week anatomy scan

  • Drink lots of water before going to your appointment.  Having a full bladder helps with the sonogram images.
  • Expect to be there a while. It can take anywhere from 30 minutes or more to get set up and for the sonographer to get a good view of your little one.
  • Be open about how you’re feeling. You may be sitting in a less than comfortable position with your belly exposed for some time. If you’re uncomfortable or need to get up or use the restroom, let the technician know so you can get more comfortable.


During your first trimester, you will have had tests done that show whether your baby could be born with a genetic disorder such as Down syndrome. In the second trimester, certain mothers will be advised to have a screening called amniocentesis, especially if they…

  • Are 35 or older
  • Have had abnormal results from previous tests 
  • Already have a child with a genetic disorder
  • Have a family history of certain genetic disorders

For this test, your doctor will perform an ultrasound to locate your baby and the amniotic sac. Then he will insert a needle into your abdomen and into the amniotic sac to withdraw about two tablespoons of amniotic fluid. The procedure should take about 30 minutes, and you’ll have to take it easy for the rest of the day and not do anything too strenuous in the couple of days afterward.

You will typically get the results from your amnio test within seven to 14 days. Studies have found amnio to be 99 percent accurate in diagnosing Down syndrome. The risks for miscarriage during the test itself are very low, but you should still have a conversation with your doctor about any and all possibilities — during the test and potential results — when considering having amnio.

The Quad Screen

Some expecting moms are offered a type of prenatal testing called NIPT in their first trimester. This test is extremely accurate at detecting whether your baby could be born with a disorder like Down syndrome, Edward syndrome, or Patau syndrome. However, NIPT is not available everywhere, so you may be offered a different type of genetic test called the quad screen.

The quad screen is a blood test done in the second trimester that measures the amount of four substances, all of which are produced by the fetus and placenta into the mother’s bloodstream. These substances are…

  • Alpha-fetoprotein (AFP)
  • Human chorionic gonadotropin (hCG)
  • Inhibin A
  • Estriol

The results to your quad screen won’t show definitively whether your baby will have a genetic disorder, but it can you tell if the risk is higher. The quad screen tests for these abnormalities:

While the quad screen doesn’t have as high detection rate as other prenatal screens, it can detect a higher risk for about 85% of neural tube defects and about 80% of Down syndrome cases. If your quad screen shows abnormalities, your doctor will want to run follow up tests to find out more.

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