Blood Tests in Early Pregnancy

A healthy pregnant woman stands outside amongst trees

Blood tests play an integral role in providing information during the early stages of pregnancy. They can determine pregnancy, and even show how far along you are. Specific blood tests keep your doctor up to date on the progression of your pregnancy. They also help manage you and your baby’s health. When you’re pregnant, it’s not just ultrasounds that are important! 

Blood Tests for Pregnancy 

Using a blood test to determine pregnancy is more accurate than an at-home urine-based pregnancy test. There are two types of blood tests to check if you’re pregnant, but they’re both looking for the same hormone. This hormone, the human chorionic gonadotropin or (hCG), is only found in the body during pregnancy. The qualitative hCG blood test detects any of this hormone, giving you a “yes or no” result. The quantitative hCG blood test measures the actual amount of hormone, so gives you more information about your pregnancy. If your blood test shows higher or lower levels of hCG than your doctor was expecting, it could mean that the progression of your pregnancy or due date is different than you thought. It could also mean that you need further testing to determine why the results show unusual levels.

Blood Typing for ABO Type in Early Pregnancy

An important blood test when you’re pregnant is to check which ABO blood type you are. This can be A, B, AB, or O. These blood types are characterized by different proteins attached to your red blood cells. If two incompatible types of blood are exposed to each other through blood donation or pregnancy, the proteins are perceived as a threat to an immune system that doesn’t recognize them. When a pregnant person has a different blood type than their baby, their immune system could create antibodies against the proteins of the baby’s blood type. These antibodies can reach the baby through the placenta, putting the baby’s health at risk after it’s born.

ABO Compatibility

The reason it’s important to have your blood tested for ABO type is to assess the level of compatibility and risk between mother and baby. Different blood types don’t necessarily mean incompatibility. But, if the two have incompatible blood types, there is a risk for the baby to develop hemolytic disease of the newborn or HDN. HDN related to incompatible blood types is usually quite treatable. It can result in jaundice in newborns. The way to treat jaundice is through increasing feeding frequency, or through light therapy.

Blood Typing for Rh Protein in Early Pregnancy

In addition to ABO type, a test for blood typing also checks whether you are Rh positive or Rh negative. Rh is a different protein that some people have and some people do not have in their red blood cells. You may be familiar with “positive and negative” associated with blood type. For example, if someone’s blood type is AB+, their blood type is AB and they do have Rh proteins in their red blood cells. If a pregnant person is Rh negative and their baby is Rh positive, this can cause complications like in ABO blood type compatibility. The immune system of the pregnant person produces antibodies against the Rh proteins from their baby’s red blood cells.

Rh Compatibility

If there is an incompatibility between a pregnant person related to Rh protein, this can be more serious than an ABO incompatibility. Because the health of the baby is more at risk for this type of incompatibility, a doctor will treat this issue before the baby is born. In the case where a pregnant person is producing antibodies against the red blood cells of their baby due to Rh proteins, an injection is ordered. This injection “hides” the proteins present in the baby. The result is that the immune system of the pregnant person stops producing more antibodies.

Antibody Screening

Antibodies may exist in a pregnant person for reasons other than blood type or Rh incompatibility. They can be present from a previous pregnancy, or from a previous blood transfusion. Because of these various factors, pregnant people can be screened for antibodies to ensure that their unborn baby is not at risk. If these antibodies are present, the baby will be monitored closely and may need medical intervention before the due date. This could come in the form of a blood transfusion (through the umbilical cord), or through early delivery.

Other Blood Tests Available in Early Pregnancy

To ensure that your doctor is getting a clear picture of your health, they may order other blood tests to track your pregnancy. These include checking for anemia, diseases such as HIV, hepatitis, and certain sexually transmitted diseases. Tests for immunity to German measles and chickenpox may also be ordered. This is because should you contract either, it could be dangerous for the health of your baby.

Testing for Fetal Abnormalities

In addition to routine blood tests and ultrasounds in your first trimester, you or your doctor can request other maternal serum tests. One of these tests measures levels of pregnancy-related plasma protein A, a protein that the placenta produces. If you previously haven’t had a quantitative hCG blood test, this may be ordered too. If either of these blood tests show abnormal levels, they can point to chromosomal abnormalities.

Additional Testing

Additional blood tests are available to pregnant people who wish to learn more about their pregnancy. Tests are also available for those who are at risk of genetic disorders. Your doctor may suggest certain tests if genetic disorders run in your family, or if they determine you may be at a higher risk. Your doctor may also suggest a blood test to determine blood sugar levels. This can be a measure to protect you and your baby if you are more at risk for gestational diabetes. This can be because of your own medical history, or because of your family’s medical history. Discuss these additional tests with your doctor, who can help you determine what is right for you, your health, and the health of your baby.

Your Healthy Pregnancy

With over 3,500 tests available, Your Health Lab offers many options and resources for monitoring your health and the health of your baby. Many tests are routine, and more are available depending on your preferences and your doctor’s recommendation. Speak to your doctor or healthcare provider to decide which is right for you.

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