Blood Tests During Pregnancy: What You Need to Know

Highlights

• Blood tests are offered during pregnancy to ensure the well-being of you and your baby.
• Most of these tests can be done early in your pregnancy.
• Your doctor might offer blood tests to check your blood type and if you have any infections or conditions.
• Blood tests are important for monitoring your health and your baby’s health throughout pregnancy.

In This Article

• What Blood Tests Are Done During Pregnancy
• Types of Blood Tests During Pregnancy
• Blood Group and Rhesus Factor Testing
• Anemia and Iron Deficiency Measurement
• Infection Screening During Pregnancy
• Gestational Diabetes Testing
• Vitamin D Level Testing
• Prenatal Screening and Testing
• Tools and Assistance

What Blood Tests Are Done During Pregnancy

Throughout your pregnancy, you will have different tests done, including blood tests, to ensure the well-being of you and your baby. As part of your antenatal care, you’ll be offered several blood tests. These will:

• Confirm your pregnancy
• Check your blood group
• Identify any health issues that may cause a problem during your pregnancy or after birth

Some blood tests are offered to everyone, while others are only recommended if you have a higher risk of certain infections or conditions. It’s a good idea to talk to your doctor or midwife about the benefits and risks of antenatal tests. You can ask them any questions you may have about tests during pregnancy. Attending routine antenatal appointments throughout pregnancy is important. This allows early detection of potential complications.

Types of Blood Tests During Pregnancy

In early pregnancy, usually at your first antenatal visit, you will have tests for:

• Your blood type
• Iron deficiency and your hemoglobin levels
• Sexually transmitted diseases and other infections
• Blood sugar levels

Around your third trimester, you may be tested again for gestational diabetes and your hemoglobin levels. You may also need more tests related to your blood group.

Blood Group and Rhesus Factor Testing

There are four blood types: A, B, AB, or O. You will have a blood test early in your pregnancy to determine your blood type. Knowing your blood group is useful in case you need a blood transfusion due to anemia or heavy bleeding (hemorrhage) during pregnancy or birth.

Along with your blood group, you will also find out your Rhesus (RhD) factor. You can be RhD positive or negative.

If you are RhD negative and your baby is RhD positive, your body may produce antibodies against your baby’s blood. These antibodies can cross the placenta and destroy your baby’s red blood cells, leading to hemolytic disease of the newborn. This condition usually does not affect a first pregnancy but can cause complications in future pregnancies with RhD-positive babies.

If you are RhD negative, you will be offered anti-D injections at 28 and 34 weeks of pregnancy to prevent antibody production. This is a safe and effective way to protect your baby.

Anemia and Iron Deficiency Measurement

During pregnancy, your body needs extra iron to support the increased blood volume necessary for you and your baby. If you have low iron levels, you can develop anemia. This means your red blood cells cannot carry enough oxygen, making you feel tired and increasing the risk of complications during labor and birth.

A full blood count test is typically done at your first antenatal visit and again around 28 weeks to check your hemoglobin levels.

Factors that increase the risk of anemia include:

• A history of anemia
• A diet low in vitamin B12 and folate
• A vegetarian or vegan diet
• Closely spaced pregnancies
• Severe morning sickness (hyperemesis gravidarum)

Your doctor or midwife may recommend iron supplements or infusions if needed.

Infection Screening During Pregnancy

Blood tests during pregnancy screen for several infections that may affect your baby. These include:

• Rubella (German measles)
• Syphilis
• Hepatitis B
• Hepatitis C
• HIV (human immunodeficiency virus)
• Group B streptococcus
• Cytomegalovirus

Even if your test results are negative, it’s important to continue taking precautions, as you can still contract infections later in pregnancy. Your doctor or midwife will discuss the results and recommend any necessary treatments during pregnancy and after birth.

Gestational Diabetes Testing

Gestational diabetes (GDM) is a type of diabetes that develops during pregnancy. It occurs when there is too much glucose (sugar) in your blood. Around 1 in 10 pregnant people develop GDM.

The oral glucose tolerance test (OGTT) is used to diagnose gestational diabetes. The test involves:

• Fasting overnight
• Taking a blood test
• Drinking a glucose-containing liquid
• Taking additional blood tests one and two hours later

You will need to stay at the testing center for the duration of the test.

Gestational diabetes usually develops between 24 and 28 weeks and often disappears after birth. However, if you have had GDM, you are at a higher risk of developing type 2 diabetes later in life. If diagnosed, your healthcare provider will help you manage the condition to ensure a healthy pregnancy.

Vitamin D Level Testing

Vitamin D is important during pregnancy for both you and your baby. It helps your body absorb calcium and supports the development of your baby’s bones. A blood test can measure your vitamin D levels. Sources of vitamin D include:

• Sun exposure
• Foods such as eggs, fish, and dairy products

If your levels are low, your doctor or midwife may recommend vitamin D supplements. In some cases, supplementation may be needed even after pregnancy.

Prenatal Screening and Testing

Prenatal screening tests look for signs that your baby might have a higher chance of certain health conditions. These include:

• Extra chromosomes, such as Down syndrome and Edwards syndrome
• Neural tube defects, such as spina bifida
• Other congenital disorders

Screening for chromosomal differences is done through both ultrasound and blood tests. These tests are typically performed between 9 and 13 weeks and again at 14 to 20 weeks.

Participation in prenatal screening is optional. You can discuss your options with your doctor, midwife, or genetic counselor.

Tools and Assistance

There are several tools and resources available to support you during your pregnancy, especially when it comes to understanding and preparing for blood tests. Some of the tools available include:

• Health monitoring tools: There are various apps and devices designed to help monitor your pregnancy progress, track doctor appointments, and keep track of your test results.
• Blood test guidance: Your healthcare provider can guide you on which blood tests are needed during your pregnancy and what each test is for. Be sure to ask about the timing of these tests and what you should expect.
• Dietary support: If you need to manage conditions like anemia or gestational diabetes, your healthcare provider or dietitian can provide personalized dietary advice and supplement recommendations.
• Prenatal care advice: You can also access information on general prenatal care, including the importance of attending all antenatal appointments and preparing for possible tests or treatments.
• Support groups and counseling: If you have any concerns or need additional emotional support, many healthcare centers provide counseling services, support groups, or resources for connecting with other expectant parents.