Questions About Prenatal Testing? These Are the Top Lab Values to Monitor During Pregnancy

Lauren Bedosky
Medically Reviewed
May 17, 2021

To safeguard you and your baby, it’s important to keep tabs on certain health markers throughout your pregnancy. This is where prenatal testing comes into play. Read on to learn what they are and how they can optimize your pregnancy , delivery, and postpartum experience.

What is prenatal testing?

“Prenatal tests are a panel of blood work that looks into different aspects of your health that can be addressed or modified during pregnancy,” says Stephanie Wallman , D.O., a family medicine physician at Parsley Health.

We’ll get into the specifics of these shortly, but at Parsley Health tests include:

  • Thyroid panel
  • Nutrient panel
  • Insulin and sugar levels
  • Complete blood count/anemia markers
  • Heavy metal markers

If test results indicate something’s amiss, your Parsley Health doctor will work with you to ensure your pregnancy is as healthy as possible. Parsley Health providers conduct prenatal tests with the goal of optimizing your health. “We believe that a mom who is optimized in her nutrients and health markers will have fewer adverse outcomes, as well as a healthy pregnancy and delivery,” Wallman explains.

Obstetricians (OBs) typically run prenatal tests that focus on the baby’s health at various stages of pregnancy. But also important are the nutrient and hormone issues affecting the mom’s health, according to Dr. Wallman. Combining the expertise of your OB and Parsley Health provider will fill in any possible gaps in your pregnancy and postpartum care.

How often should prenatal testing occur?

Tests are typically done around 8-10 weeks (first trimester), 22-24 weeks (second trimester), and 35-37 weeks (third trimester). According to Wallman, your doctor will pay close attention to specific markers to prepare for significant events that happen during each trimester. Parsley Health clinicians will also check your blood panel 8-10 weeks after delivery to support recovery, as well as troubleshoot any issues with breastfeeding or sleep .

What are the normal lab values during pregnancy?

Each of the following tests provides you and your doctor with the information you need to ensure a healthy pregnancy, delivery, and recovery. If your results don’t match the normal lab values for each health marker, your Parsley Health provider will help steer you along the right path.

Thyroid panel

Parsley Health providers take thyroid panels to keep tabs on the hormones made by your thyroid (a butterfly-shaped gland in your throat) and pituitary gland (a small pea-sized gland at the base of your brain). These hormones play a big role in building your baby’s brain and nervous system during pregnancy, according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). With such high demand, it’s fairly common for hormone levels to run low as the pregnancy progresses.

Your body will demand more and more thyroid hormone as the pregnancy goes on, but thyroid function is most affected after delivery. So, “it’s important to follow these numbers past pregnancy to ensure that the thyroid stays stable after the baby is born,” Wallman says.

Normal lab values:The thyroid panel will measure a few different hormones, including the thyroid-stimulating hormone (TSH), triiodothyronine (T3) hormone, Free T4, and Free T3. Ideally, for pregnancy the TSH should be between 0.5 and 2.5 ulU/mL and the Free T3 should be between 3.0-3.5 pg/mL, and Free T4 should be 1-1.5 Parsley Health clinicians check hormone levels during each trimester, as well as 8-10 weeks postpartum.

Nutrient panel

Your doctor will use the nutrient panel to keep a close eye on key vitamins and minerals at different stages of your pregnancy. Folate, for example, is a B-vitamin that’s vital to healthy growth. “Adequate folate levels ensure that there are no neural tube [birth] defects like spina bifida,” Wallman says. Folate also helps keep your energy levels up. “So if you’re deficient, you’re just going to have extra fatigue on top of what you already feel being pregnant,” Wallman says.

Another important nutrient to watch during pregnancy is Vitamin D , a fat-soluble vitamin that helps your immune system fight off harmful bacteria and viruses. “You can’t really take medications during pregnancy, so if you’re getting sick all the time, you just have to grin and bear it,” Wallman says. “But if you have good vitamin D levels , it will decrease the frequency of getting sick.”

Normal lab values:Optimal folate levels should be around 600 ng/mL, while vitamin D should be between 40-60 ng/mL.

Insulin and blood sugar levels

Some women develop diabetes for the first time during pregnancy. This is known as gestational diabetes, and it often occurs in the middle of pregnancy.

According to the CDC , gestational diabetes can lead to high blood pressure (preeclampsia), low blood sugar (hypoglycemia), and a higher likelihood of needing a Cesarean section (C-section). If your diabetes isn’t well controlled, your baby can develop high blood sugar as well. This extra sugar can cause your baby to grow extra large, which can lead to discomfort, problems during delivery, and possible nerve damage to the baby.

Unfortunately, many OBs only test your insulin and blood sugar levels once, and by the time they do, there’s often an issue already. “And at that point, there’s little you can do to prevent any complications,” Wallman says. At Parsley Health, doctors test your insulin and fasting blood sugar earlier, so you can make any lifestyle or medication changes needed to prevent gestational diabetes before it happens.

Normal lab values:Insulin levels should be around 2.5-5, ideally, and the fasting blood sugar between 75-85 mg/dL.

Complete blood count/anemia markers

Your doctor will take a complete blood count (CBC) to check the number of different types of cells that make up your blood. This includes your oxygen-carrying red blood cells, disease-fighting white blood cells, and blood-clotting platelets.

They will also check your levels of ferritin, which is a blood protein that contains iron. According to Wallman, measuring your ferritin levels in addition to taking a CBC can help your doc catch iron deficiencies before you become anemic. Anemia, a fatigue-inducing condition where you don’t have enough healthy red blood cells to carry oxygen throughout your body, is incredibly common in pregnant women. “You’re building a baby and a whole second blood supply, and that takes a lot of iron to do,” Wallman says.

Low iron levels not only make you feel tired and weak, but anemia is also linked to an increased risk of preterm delivery. To top it off, the risk of iron deficiency in the US just about doubles every trimester, according to Wallman. At the other end of the spectrum, high levels of iron can cause issues during pregnancy, too. “This is why [ferritin] should be monitored regardless,” Wallman says.

Normal lab values: An optimal ferritin range going into pregnancy is 100-120 ng/mL, and during pregnancy, it’s 50-100 ng/mL.

Heavy metal markers

Getting heavy metals like lead and mercury into your system during pregnancy can increase your odds of miscarriage, stillbirth, or birth defects, according to the CDC . (Here’s what all women should know about the environmental risks that affect pregnancy .)

Heavy metals can sneak into your system via food (like seafood) and water, or even through paints. You can also get exposed to heavy metals if you work in construction or home renovation and breathe in dust or fumes from the materials used. Your baby is at most risk of toxins during the first trimester, which is why your Parsley Health doctor will test for heavy metals at this time, Wallman says.

Normal lab values: Mercury and lead levels should be 0. If your results indicate there are any heavy metals in your system, your Parsley Health doctor will help you figure out where it’s coming from so you can cut off the source. Don’t try to detox, though. “Doing a detox protocol is not an option during pregnancy, as the placenta and the breast milk are potential locations that the body can detoxify those metals into,” Wallman says.

The support you need during pregnancy

If your clinician at Parsley determines anything is off during prenatal testing, they may adjust your prenatal vitamins, help you make nutritional changes, or refer you to your OBGYN for any major abnormalities. Working with both a clinician and health coach at Parsley Health during your pregnancy can give you the extra support and reassurance you need for a healthy pregnancy.

Lauren Bedosky

Lauren Bedosky is a freelance health and fitness writer who specializes in running, strength training, and nutrition. She writes for a variety of national publications and businesses, including Men’s Health, MyFitnessPal, Livestrong, and Women’s Running. Lauren lives in Brooklyn Park, Minnesota, with her husband and their three dogs.

Read full bio
readiness quiz

Get a snapshot of your health - right now.

Take our quiz to get your symptom score and start uncovering the why behind your symptoms.

Related Posts
10 TikTok Health Trends Worth Trying—and Avoiding
Get “Prescription for Happiness” and Reach a New Level of Energy, Clarity, and Calm
Four Smart Ways to Track Your Heart Health Today
12 Gifts For The Well-Being Seekers In Your Life
How to Select the Right Health Coach for You
Doctor examining patient


Our leading medical providers and health coaches heal the root cause of health concerns with a personalized care plan and year-round support. Our root-cause resolution medicine has helped thousands feel better, with 85% of members reducing symptoms in their first year.

Parsley Health medical providers are trained to treat the root cause of complex, chronic conditions and symptoms. Ready to start feeling better?

Get Symptom Score