A First-Time Mom’s Guide to Types of Blood Tests in Pregnancy

So you’ve peed on a stick, seen those two lines, and now you’re suddenly navigating terms like “hCG,” “CBC,” and “Rh factor.” Confused? You’re not alone.

Nearly 97% of pregnant women in the U.S. undergo multiple blood tests during pregnancy — and for good reason (CDC, 2022). These tests aren't just routine—they’re key to keeping you and your baby healthy from day one.

In this guide, we’ll break down what happens at every stage, why it matters, and what questions to actually ask your OB (yes, there are dumb questions—but this isn’t one of them).

Pregnancy Care Starts with Testing: What to Expect Throughout

Your first prenatal visit is a big deal. It helps your doctor get a full picture of your health and your baby’s development.  

If you're pregnant on the pill, don’t worry—this visit is designed to figure out what your body needs next. Many women discover they're expecting even while using birth control. You’re not alone.

Your First Prenatal Visit

1. Pregnancy tests: Your doctor may confirm your pregnancy with a urine sample or a blood test. These tests check your pregnancy hormone levels like human chorionic gonadotropin (hCG).
2. Blood tests in pregnancy: These are routine. A small sample of blood checks your blood type, Rh factor, red and white blood cells, and more. If you're Rh-negative, you may need treatment to protect your unborn baby. A full blood count is usually done at the first antenatal visit and again at around 28 weeks of pregnancy to check haemoglobin levels.
3. Prenatal screening: This includes screening tests for birth defects, genetic disorders, and conditions like down syndrome or neural tube defects. These tests help doctors spot issues early. “Screening doesn’t mean there’s a problem—it just helps us decide if we need further tests,” says Dr. Anshu Agrawal, an expert in pregnancy care.
4. Family history: Your doctor may ask about your family history to see if you have certain risk factors like carrying twins or past health conditions. If needed, they might refer you to a genetic counsellor.

Blood Tests by Trimester: A Timeline for Pregnant Women

Blood tests in pregnancy are more than just routine. They help doctors spot problems early and keep pregnant women and their unborn babies healthy. These tests are done at different times in pregnancy. Each one checks for something important.

1. First Trimester (Weeks 1–12): Early Checks for a Healthy Start

Early testing helps detect risks like anemia, infections, and blood type incompatibility.

Key tests include:

• Blood type and Rh factor – Critical to avoid Rh incompatibility with the baby.
• Complete blood count (CBC) – Checks red blood cells and iron levels. Testing for anemia during pregnancy ensures that mothers maintain adequate iron levels to support blood volume increases.
• HIV, hepatitis B, and syphilis screening – Ensures no hidden infections.
• hCG levels – Confirms pregnancy and checks viability.
• Thyroid function test – Especially important if you have symptoms or a history of thyroid issues.

Bonus tip: Ask about prenatal screening for Down syndrome and other chromosomal conditions—many are optional but time-sensitive.

Why Your Blood Group Matters During Pregnancy

Knowing your blood group is one of the first things your doctor will check. It’s not just a formality—it can seriously affect your pregnancy care. Here’s why:

• Your blood type is either A, B, AB, or O—and you’re either Rh-positive or Rh-negative.
• If you're Rh-negative and your baby is Rh-positive, your body might see your baby's blood as a “threat.” This can lead to something called Rh incompatibility.
• Your doctor may give you a shot called Rh immunoglobulin to stop this from happening. It protects both you and your baby’s blood from mixing and causing problems. You will be offered the anti-D injection at 28 weeks and 34 weeks of pregnancy if you are RhD negative.
• This test also helps doctors prepare in case of serious illness, blood loss during delivery, or if you're carrying twins.

Doctors use a small sample of your blood to run this test early—often during your first prenatal visit.

"Blood group testing isn't just about labels—it's about preventing complications before they begin," says Dr. Anshu Agrawal, India’s leading expert in pregnancy care.

2. Second Trimester (Weeks 13–27): Deeper Screening for Baby’s Development

This stage checks how your baby is growing and screens for conditions like gestational diabetes.

Key tests include:

• Quad screen – Measures four substances to assess risk for genetic conditions.
• Oral glucose tolerance test (OGTT) – Screens for gestational diabetes, usually around week 24–28. The glucose challenge test is the first test for gestational diabetes and is usually done between weeks 24 to 28 of pregnancy.
• CBC follow-up – Checks for anemia as blood volume increases.

Add-on insights:

• If earlier results showed Rh-negative blood type, you might get an antibody screen again.
• Some doctors may recommend maternal serum alpha-fetoprotein (MSAFP) for spina bifida screening.

Understanding Gestational Diabetes in Pregnancy

Gestational diabetes is a kind of diabetes that can show up during pregnancy—even if you’ve never had it before. It usually appears in the second trimester, but doctors start watching for it early if you have certain risk factors like:

• A family history of diabetes
• Being overweight
• A previous pregnancy with high glucose levels or positive result for diabetes
• Being over age 35
• Pregnant on the pill and unaware of the timing of conception

You’ll likely take an oral glucose tolerance test (OGTT) around week 24 to 28. You'll drink a sweet liquid, then give a blood sample to check how your body handles sugar.

Why it matters:

• High sugar levels can cause birth defects, a larger baby, or even early delivery.
• It raises the risk of preterm labor, amniotic fluid issues, and long-term health issues for both you and the baby.

3. Third Trimester (Weeks 28–40): Safety Checks Before Labor

These blood tests help prepare for a safe delivery for both mother and baby.

Key tests include:

• Repeat CBC – Monitors iron and red blood cell levels before delivery.
• Group B Strep (GBS) test – While not a blood test, it’s critical and happens via a swab.
• Blood tests for clotting – Especially if you have risk factors like preeclampsia.

Other checks:

• You might need antibody screening again if you're Rh-negative.
• If you have gestational diabetes, you’ll need more frequent blood sugar monitoring.
• Vitamin D levels in pregnant women are assessed through blood tests to ensure proper calcium absorption and fetal bone development.

Types of Routine Tests During Pregnancy

1. Blood Tests

Blood tests in pregnancy are done at your first visit and several times after. A small blood sample is taken from your arm. This test can show a lot! Here’s what it checks:

• Blood type and Rh factor – This shows if your blood is A, B, AB, or O, and if it’s Rh positive or negative. If there’s a mismatch with your baby, your doctor may give you a shot to protect your baby’s blood.
• Complete blood count (CBC) – This checks red and white blood cells. It helps find anemia or infections.
• Screening test – You might be screened for HIV, hepatitis B, or syphilis.
• Pregnancy hormone – A test for human chorionic gonadotropin (hCG) checks if your pregnancy is healthy.
• Prenatal tests – These include prenatal screening for birth defects, genetic conditions, and neural tube defects.
• If anything is unclear, doctors may ask for diagnostic tests or more tests to confirm results.

2. Urine Tests

At each visit, you'll give a urine sample. Don't worry—it’s quick and easy. Urine tests look for:

• Sugar levels – High sugar may mean gestational diabetes.
• Protein – Too much could signal a serious illness like preeclampsia.
• Signs of infection – These are often found early, before you feel sick.

These tests help catch health issues that can affect you or the baby.

3. Ultrasound Scans

Gives a real-time picture of your baby’s growth and position.

Common scans:

• Dating scan (around 6–9 weeks) – Confirms how far along you are.
• Nuchal translucency (11–14 weeks) – Screens for Down syndrome.
• Anatomy scan (18–22 weeks) – Checks the baby’s organs and limbs.

4. Screening Tests for Genetic Conditions

Helps you understand risks for conditions like Down syndrome or spina bifida.

Types:

• First-trimester combined screening – Includes blood work + nuchal ultrasound. Nuchal translucency screening checks the back of the fetal neck for extra fluid or thickening using ultrasound.
• Second-trimester quad screen – Checks hormone and protein levels.
• Non-invasive prenatal testing (NIPT) – An advanced blood test for chromosomal issues.

5. Glucose Tolerance Test

This test checks for gestational diabetes. It's common and usually happens in the second trimester. Here’s what happens:

• You drink a sugary drink at the clinic.
• After a few hours, a nurse will take your blood sample to check your glucose levels.
• If it’s high, that may mean you have gestational diabetes.

This condition can lead to a larger baby, preterm labor, or other health issues—but only if not managed. Your doctor will likely suggest diet changes, mild exercise, and more tests if needed.

“Most moms handle it with simple changes,” says Dr. Anshu Agrawal. “It’s not your fault—it’s your hormones.”

6. Group B Strep Test (GBS)

This test looks for a kind of bacteria called Group B streptococcus. It’s not harmful to you but could be dangerous for the baby during birth. Key things to know:

• It’s not a blood test, but it’s still very important.
• It’s done around week 36 or later.
• A swab is gently taken from your vagina and rectum.
• If the test is positive, you’ll get antibiotics during labor to protect the baby.

Don’t worry—many women test positive, and treatment works well. It’s quick, painless, and protects your baby’s blood cells from infection.

Diagnostic Tests vs. Screening Tests: What’s the Difference?

Prenatal Screening vs. Genetic Testing

Key Blood Tests and What They Detect

Tests for Infectious Diseases

1. Hepatitis B Surface Antigen (HBsAg) Test

This test checks if you have hepatitis B, a virus that can pass to your baby during birth. A positive result means you carry the virus, even if you don’t feel sick. Here’s how it works:

• A blood sample is taken at your first prenatal visit.
• Your doctor will review your test results and, if needed, give your baby a vaccine right after birth.
• If you're at increased risk (like if you've had liver problems), your healthcare provider may recommend more tests or medication.

2. HIV (Human Immunodeficiency Virus) Test

Testing for HIV is a key part of your diagnostic tests in early pregnancy. This virus can pass to your baby during birth or breastfeeding. Why it matters:

• Early treatment can lower the chance of your baby getting HIV to less than 1%.
• The test is safe and quick, with no harm to you or the baby.

3. Syphilis Blood Test (RPR or VDRL)

Syphilis is a serious infection. It can cause birth defects, preterm labor, or even stillbirth if untreated. Here’s what happens:

• A fluid sample (blood) is checked using an RPR or VDRL test.
• If your test is positive, your doctor will confirm it with a second diagnostic test.
• Treatment with antibiotics works well when caught early—even in early pregnancy.

4. Hepatitis C Antibody Test

Hepatitis C is a virus that can affect your liver. If you have it, it can pass to your baby during delivery. What the test does:

• A blood sample is taken to look for hepatitis C antibodies.
• If antibodies are found, a diagnostic test will check if the virus is active.
• This helps plan safe care for delivery.

“Don’t assume you’re safe because you feel okay,” says Dr. Anshu Agrawal. “We screen because infection doesn’t always mean symptoms.”

5. Rubella Immunity Test

Rubella (German measles) can be dangerous for your baby in early pregnancy. It can cause birth defects if caught while pregnant. This test checks:

• Whether you are immune from a past vaccine or infection.
• If you are not immune, your doctor will make a note to vaccinate after birth, since you can’t get the shot while pregnant.

This is a good time to talk to your doctor about any folic acid or vitamin supplements you’re taking, too.

6. Toxoplasmosis Test (if needed)

Toxoplasmosis is a disease you can catch from undercooked meat or cat litter. It rarely causes problems in adults—but it can seriously harm a baby. What to know:

• Not everyone needs this test. Your healthcare provider will suggest it based on risk factors.
• It may involve checking a fluid sample or running test measures on your blood.

If your test results are positive, your doctor will discuss more tests and next steps to prevent passing it to your unborn baby.

Screening for Genetic Conditions and Birth Defects

During pregnancy, you want to make sure your baby is growing healthy. One of the best ways to do that is through blood tests in pregnancy. These are not just routine—they’re important tools that help find early signs of birth defects and genetic conditions.

These are called pregnancy screening tests. Most are done during your first trimester, between weeks 10 and 13. A blood sample is taken from your arm. Sometimes, the doctor may also suggest testing amniotic fluid, especially if there's a family history or the blood tests show something unusual.

Here’s what they help check for:

• Down syndrome
• Spina bifida
• Neural tube defects
• Chromosomal problems like trisomy 18 or 13

These tests don’t give a “yes” or “no” answer. Instead, they tell you the risk—whether it’s low or high. If a screening test shows a higher risk, your healthcare provider might suggest diagnostic tests to confirm.

Expert Advice from Dr. Anshu Agrawal: Your Pregnancy Testing Partner

​Dr. Anshu Agarwal is a highly respected gynecologist and obstetrician based in Ranchi, India, with over 18 years of experience in women's health. Her extensive expertise, particularly in fertility treatments and high-risk obstetrics, makes her an excellent partner for pregnancy testing and care.

Dr. Agarwal offers a comprehensive range of services that are crucial for pregnancy care:​

• Routine Gynecological Checkups: Regular screenings and exams to ensure reproductive health and early detection of potential issues.​
• Prenatal Care and Delivery Services: Comprehensive care throughout pregnancy, including monitoring fetal development and managing any complications.​
• High-Risk Obstetrics: Specialized care for pregnancies with increased risk factors, ensuring both maternal and fetal health. ​Infertility Treatment and Counseling: Personalized approaches to help women conceive, including non-IVF options.​

Her clinic is equipped with advanced diagnostic tools, including blood tests and ultrasound imaging, to provide accurate and timely information about your pregnancy

Patient testimonials and expert insights on diagnostic accuracy:

Patients consistently praise Dr. Agarwal for her compassionate care and diagnostic precision:​

• "We have been trying for 3 years to have a child... we got good advice from her clinic... today, our baby boy will be delivered in Jan 2024." – Mannu Kispotta, Ranchi​
• "Under treatment in PARAS HEC HOSPITAL... baby conceived after eight years... today, me & my family are happy." – Swati Tiwary, Ranchi​

These testimonials highlight her ability to guide patients through complex fertility challenges with empathy and expertise.

Book your pregnancy check today with confidence:

Embarking on your pregnancy journey with Dr. Anshu Agarwal ensures you receive personalized, expert care every step of the way. Her clinic offers a welcoming environment where your health and well-being are the top priorities.​

To schedule an appointment:

• Phone: 072939 37999​
• Address: Medifirst Hospital, SubPlot No.2703/1 and 2703/2, Plot No. 2703, Booty Rd, near Suryodaya Apartment, Bariatu, Ranchi, Jharkhand 834009
• Visit this site to book an appointment: https://medifirst.zohobookings.in/#/263988000000040014

Spotting the Signs: What to Know About Ectopic Pregnancy

An ectopic pregnancy happens when a fertilized egg grows outside the uterus, usually in the fallopian tube. It’s a serious condition that needs fast medical care. Some blood tests are offered to everyone during pregnancy to monitor for such conditions and ensure maternal and fetal health.

It’s not always easy to spot early on. That’s why blood tests in pregnancy matter so much. These tests help your healthcare provider see if your pregnancy hormone levels are rising normally.

How is it detected?

• Your doctor may order several blood tests over a few days to track your hCG (human chorionic gonadotropin) levels.
• They’ll also use an ultrasound to check where the baby is growing.
• If things look off but not clear, your health care professional may order more tests to confirm.

Sometimes, pregnancy tests can show a false negative, especially if you test too early. That’s why follow-up blood tests and checkups are so important.

Signs to Watch For

Tell your doctor right away if you notice:

• Sharp pain in your belly or lower back
• Dizziness or fainting
• Vaginal bleeding that doesn’t feel right

These could be signs of a problem. Fast action can save your health and even your life.

“Catching an ectopic pregnancy early can prevent serious complications,” says Dr. Anshu Agrawal, a trusted healthcare provider in India. “Never ignore pain or odd symptoms in early pregnancy.”

Frequently Asked Questions

1. Do all pregnant women need the same tests?

• Not always. While most pregnant women will get the same basic blood tests in pregnancy, some may need extra tests. It depends on your health, family history, and risk factors.
• Your healthcare provider will decide what’s right for you. You might get different tests if you’re carrying twins, have a chronic condition, or had problems in a past pregnancy.

2. What does a false positive mean?

• A false positive means a test says something is wrong—but later, it turns out everything is fine. This can happen with screening tests, like those that check for birth defects.
• That’s why doctors often follow up with diagnostic tests to confirm. It’s stressful, but try not to panic. A second test usually clears things up.

3. Can tests predict preterm labor or other complications?

• Some blood tests in pregnancy and urine tests can point to possible issues, like gestational diabetes or infections.
• These don’t always mean you’ll go into early labor, but they can help doctors watch you more closely. If results show abnormal results, your doctor may suggest further tests or more frequent visits.

4. How do you confirm 100% pregnancy?

• The most reliable way is through pregnancy tests and blood tests. Home tests check for the pregnancy hormone (hCG).
• But if there's any doubt—like spotting or pain—your doctor may run several blood tests and do an ultrasound to be sure. It’s rare, but sometimes a false negative can happen early on, especially if you test too soon.

Blood tests in pregnancy are more than just routine—they help catch issues early, protect your baby, and guide your care every step of the way. From checking for birth defects to monitoring for gestational diabetes, each test has a purpose. Book your checkup today and move forward with confidence. Schedule here.

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