Medical Tests You Can Expect During Pregnancy


Megan Freedman

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Diagnostics of Pregnancy

When it comes to having a baby these days, women have several new tools and tests available that can provide a wealth of very useful information along the way. Truly, this is not your mother’s pregnancy.

At times this may seem like a dizzying amount of screening, but good prenatal care can help rule out possible health problems in you or your unborn baby or prevent problems during delivery. Many of these tests are routinely done for all pregnant women. Others are ordered based on factors such as your age, personal or family health history, ethnic background, or the results of other medical tests you’ve had. 

Here’s a rundown of the medical tests you can expect during each trimester of pregnancy. Talk with your doctor or nurse-midwife about which tests are best for you based on their risks and benefits, as well as your own health needs. 

Test Throughout Pregnancy (Weeks 1-40)

Get used to these screenings: You’ll be doing them at most (or all) of your prenatal appointments.

  • Urine test. Your OB team will screen your urine for signs of urinary tract infection, diabetes, and preeclampsia.
  • Blood pressure check. It’s important to monitor your blood pressure frequently during pregnancy. High blood pressure can lead to kidney damage, early delivery of the baby, and low birth weight.

  • Weight check. You’ll step on the scale at each visit to ensure you’re gaining weight at the right pace. Proper weight gain during pregnancy helps the baby grow, lowers the mother’s risk of contracting gestational diabetes, and helps prevent premature birth and low birth weight. 

First Trimester Tests (Weeks 1–12)

Tests during this phase will rule out pre-existing conditions you may bring to the pregnancy and give you a first look at your unborn baby. Even at such a tiny size, the fetus can already provide valuable information through the DNA he or she has started contributing to your own bloodstream.

  • Early ultrasound. This test uses sound waves to create a picture of your baby on a monitor. An ultrasound in your first trimester confirms you’re pregnant and how many babies you are carrying. It also helps your healthcare provider calculate your due date. Timing: Weeks 6-9

  • Complete blood count (CBC). This blood test searches for signs of anemia (low red blood cell count). Anemia can make you more likely to have infections, preterm delivery, and a low birth weight baby. Timing: Weeks 6-12

  • Rh factor test. This blood test will screen you for Rh disease, which in very rare cases can lead to complications and miscarriage. Timing: Weeks 6-12

  • Test for infections. A blood test will confirm you don’t have infections that can cause complications for a growing fetus, including HIV (tested with your consent), syphilis, chlamydia, rubella (German measles), tuberculosis, or hepatitis. Timing: Weeks 6-12

  • Cell-free fetal DNA testing (noninvasive prenatal testing or NIPT). This screening checks your blood for your baby’s DNA to see if he or she has certain genetic conditions or chromosome disorders, such as Down syndrome. Your doctor may recommend it if you have risk factors, such as being older than 35 or if you’ve already had a baby with a birth defect. This test can also determine the baby’s sex if you and your partner want to know it. Timing: After week 10

  • Chorionic villus sampling (CVS). This test uses a needle to withdraw a small piece of tissue from the placenta. For pregnancies considered high risk, CVS can be used to detect chromosomal disorders like Down syndrome and other genetic disorders, such as cystic fibrosis, a condition that affects breathing and digestion. Timing: Between weeks 10-13

  • First trimester screening or integrated screening. These birth defect screenings involve two types of tests. The first is a blood test that measures levels of certain substances in your blood, and the other is a nuchal translucency screening—an ultrasound exam that measures the thickness at the base of your unborn baby’s neck–an effective noninvasive screening test for Down syndrome. Timing: Between weeks 11 and 14

Second Trimester Tests (Weeks 13–28)

As your baby grows during this phase of pregnancy, screenings can tell more about his or her growth and development, as well as your own risk of conditions like gestational diabetes.

  • Amniocentesis. This test uses a thin needle to withdraw a small amount of amniotic fluid and cells from the amniotic sac surrounding your baby. Amniocentesis can detect genetic disorders, including Down syndrome, cystic fibrosis, and spina bifida, a condition in which an unborn baby’s spinal column doesn’t close. Timing: Between weeks 14 and 20 

  • Maternal blood screening. This test measures four substances in your blood—alpha-fetoprotein (AFP), estriol, human chorionic gonadotropin (hCG), and inhibin A—to see if your baby is at increased risk of developing heart defects, chromosome disorders, and spina bifida. Timing: Between weeks 15 and 20 

  • Anatomy scan. These ultrasounds examine several qualities of the growing baby, including its size, gender, movements, organ function, and possible birth defects. Timing: Between weeks 16 and 20 

  • Glucose challenge screening. This test determines your risk of gestational diabetes—diabetes that occurs during pregnancy. You’ll drink a sugary beverage and your blood will be tested an hour later to look for high blood sugar levels. Based on your results, your doctor may order a glucose tolerance test. This test involves fasting, then consuming a sugary drink and having your blood drawn every hour for three hours. Timing: Both tests are done between weeks 26 and 28 

Third Trimester Tests (Weeks 29–40)

You’re almost there! In addition to your routine appointment tests, these final screenings provide your doctor with valuable information that could affect the steps leading up to delivery.

  • Group B strep. This quick, painless swab test checks fluid from your cervix and rectum for harmful bacteria called group B streptococcus (GBS). If GBS is passed to your baby during birth it can cause pneumonia or serious infection. If you test positive for GBS, you’ll be given intravenous (IV) antibiotics during labor to help protect your baby from infection. Timing: Between weeks 35 and 37 

  • Biophysical profile (BPP). This test monitors your unborn baby’s overall health and helps your healthcare provider decide if your baby should be delivered early. A BPP involves two parts: an ultrasound and a nonstress test.  The ultrasound looks at your baby’s breathing, movement, muscle tone, and heart rate. During the nonstress test, you’ll wear a belt around your belly to measure your baby’s heart rate. Timing: Any time during the third trimester in which your care provider finds signs your baby’s well-being may be at risk.


Choosing a Doctor for Your Pregnancy

Whether you’re evaluating your current doctor or seeking a new one, keep these factors in mind to find the best fit for your family.
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Medical Reviewers: William C. Lloyd III, MD, FACS Last Review Date: Nov 3, 2016

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Medical References

  1. Amniocentesis. March of Dimes.
  2. Chorionic villus sampling. March of Dimes.
  3. Cystic fibrosis and pregnancy. March of Dimes.
  4. Eating For Two When Over/ Or Under Weight. American Pregnancy Association.
  5. High Blood Pressure in Pregnancy. National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health.
  6. Pregnancy Calendar. KidsHealth from Nemours.
  7. Prenatal care and tests.
  8. Prenatal Tests: First Trimester. KidsHealth from Nemours.
  9. Prenatal Tests: Second Trimester. KidsHealth from Nemours.
  10. Prenatal Tests: Third Trimester. KidsHealth from Nemours.