PregnancyHealth and SafetyLab and Blood Tests During Pregnancy

Lab and Blood Tests During Pregnancy

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As you progress through your pregnancy, there will be a range of routine lab tests that your doctor will recommend you attend to help get a better view of how you and your pregnancy are progressing. These laboratory tests are standard and occur at various times and help alert the medical team and you of any issues or infections that might be of concern and could be harmful to you or your baby.

But first, let’s get the big one out of the way: Are you squeamish about needles? Unfortunately, pregnancy requires quite a few blood draws. Take a deep breath and know that it’s all to monitor the health of your sweet baby.

Lab and blood tests through your pregnancy

Keep in mind different doctors recommend different blood work in pregnancy. Be sure to talk to your doctor about which tests they order routinely. It will probably be some version of the following:

  • 10-weeks – first prenatal labs
  • 16-weeks – Maternal Serum Alpha-Fetoprotein, or MSAFP
  • 28-weeks – Glucose Tolerance Test and Anemia Screen
  • 36-weeks – Group B Strep swab

First Prenatal Tests

Done during the first trimester at around 10 weeks, the first prenatal laboratory tests (or labs) are the most comprehensive of the labs you’ll have drawn during pregnancy. These labs will be a combination of bloodwork and some other types of tests:

Pap smear

if you haven’t gotten a pap smear in a few years, your doctor will want to do one at this visit to get you up to date. This will involve taking a small sampling of cells from your cervix to screen for atypia that may eventually lead to cervical cancer. Don’t worry, getting a pap smear while pregnant poses no risk to your baby.

STI testing

Certain sexually transmitted infections can pose a risk to a fetus. Your doctor may want to do a vaginal swab that tests for gonorrhea and chlamydia to ensure you are STI free and don’t pass anything to your unborn baby.

Type and Screen

Your doctor will be interested in knowing your blood type prior to the birth of your baby. If you have an RH negative blood type, such as AB-, you will receive a shot of RhoGAM at around 28 weeks of pregnancy. Because your baby may have a different blood type than you and be Rh positive, this shot protects you from developing antibodies against your baby’s blood.

Complete Blood Count

Sometimes called a CBC, this test takes a close look at the cells in your blood, including the amount of white and red blood cells as well as the concentration of hemoglobin and hematocrit. An abnormal CBC can indicate conditions such as anemia or infection.

Rubella Immunity Testing

Part of your blood draw will screen for Rubella immunity (if you were vaccinated as a child, you should still be immune). If you test negative, your doctor will simply have you receive the Measles, Mumps, and Rubella (MMR) vaccine post birth.

Thyroid screening

Your doctor will check your TSH, or your Thyroid Stimulating Hormone, to ensure your thyroid is working properly. TSH plays an important role in the brain development of your baby during pregnancy.

Genetic Screening

Tests like the MaterniT® 21 Test or Prequel® Prenatal Screen look for chromosomal abnormalities such as Down Syndrome. If you’re interested, these tests can also reveal the sex of your baby!

Immunizations

Your doctor will recommend that you’re up to date on vaccinations in order to keep you and your baby as healthy as can be. You should receive your flu shot if you haven’t already as well as your Covid-19 booster.

After 28 weeks, you’ll also receive the TDAP vaccine (Tetanus, Diphtheria, and Pertussis). Pertussis is commonly known as “whooping cough” and you’ll want this immunization so that antibodies can be passed to your baby in utero. Anyone who will be close to the baby in the first months of his or her life should also ensure they are up to date on this immunization.

Maternal Serum Alpha-Fetoprotein (MSAFP)

Done during weeks 16-18, the MSAFP blood draw checks for abnormalities in your baby’s AFP levels in their blood (and therefore in your blood, as well). A high MSAFP could indicate a neural tube defect such as spina bifida. A low MSAFP could indicate a chromosomal abnormality such as Down Syndrome.

 If this comes back out of the normal range, don’t panic – it is simply a screening test. Your doctor will use your results to assess your risk for these conditions. Follow up testing will be required to make a definitive diagnosis.

28-Week Labs

Around 28 weeks, in your third trimester, you will be screened for gestational diabetes, which is a condition that affects about 2-10% of pregnancies and occurs when a pregnant woman develops diabetes due to pregnancy. For this test, you’ll drink a 50-gram glucose drink and have your blood drawn exactly one hour later. If your glucose comes back high, you’ll be asked to return for the 3-Hour-Glucose Tolerance Test to confirm whether you have gestational diabetes.

Group B Strep Swab

Hooray! This one isn’t actually a blood draw, but rather a swab that your provider will take of your vaginal and rectal area.

Group B Strep is bacteria that are commonly present in our bodies. While it does not pose a risk to you, it can be dangerous for your newborn baby who could contract it from you during vaginal birth. If you test positive for GBS, worry not — your provider will simply treat you with intravenous antibiotics during labor.

Other Labs

While not routine, sometimes during pregnancy you’ll need some extra labs drawn to monitor your health and your baby’s health. Some conditions that might warrant extra labs include:

Preeclampsia

If you have a high blood pressure reading, swelling, and/or vision changes, your doctor may want to draw something called a PIH (pregnancy-induced hypertension) panel to screen you for preeclampsia, which is a dangerous condition that can occur in pregnancy. The PIH panel will check a Complete Blood Count (CBC), a Comprehensive Metabolic Panel (CMP), and a uric acid level. If you do have preeclampsia, your doctor will have you take medication and may recommend inducing labor early.

Cholestasis of pregnancy

If you’re feeling itchy but have no rash, your doctor may want to rule out a condition called intrahepatic cholestasis of pregnancy, which is a liver condition that can develop in the 3rd trimester. 

Gestational diabetes

If you develop gestational diabetes during pregnancy, or if you have certain risk factors for it, your doctor may want you to do the Glucose Tolerance Test more than just at around 28 weeks of pregnancy to ensure your blood sugar is regulated.

Needle phobia?

If you’re particularly squeamish, there are things you can do to make the blood draw as seamless as possible:

  • Drink lots of water beforehand. Staying hydrated helps the person drawing your blood in finding a good vein.
  • Bring a snack for after. Eating something sugary immediately after can combat any feelings of lightheadedness.
  • Request to lie down. Most blood draws are done while sitting upright in a chair, but lying down can prevent feeling faint. Just make sure to sit up slowly once you’re done!
  • Bring a distraction. Don’t underestimate the power of your mind! Bring your partner or a friend to chat with you during the draw, or zone out on your phone for a few minutes. It will be over before you know it.

Keep in mind, while recommended, most blood draws in pregnancy are entirely optional. Be sure to speak with your doctor if you’re considering opting out of any of the routine lab work.

In this series

First Trimester: Read our guide to the first trimester of your pregnancy.

Second Trimester: Read our guide to the second trimester of your pregnancy.

Third Trimester: Read our guide to the third trimester of your pregnancy.

Written by

Abigail Purcell, RN
Abigail Purcell, RN
Abigail is one of our expert writers and is a BSN, RN (Registered Nurse) with a wide range of experience. She has worked in Public Health, Medical-Surgical nursing, and, most recently, Paediatrics and Women’s Health. Her true passion is serving mothers and families by helping them navigate their healthcare. As a nurse writer, Abby enjoys being able to empower patients on a larger scale, using evidence-based information that is easy to access and understand.

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