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Prenatal Labs

Written By: Elizabeth Oler, MD/OB/GYN Do you really need this much blood?!

Labs during pregnancy

Many women are surprised by how many tubes of blood are needed when you are pregnant. We recommend a basic panel of labs at your first intake visit and then again later in pregnancy. These help us ensure that both you and baby are healthy. While most women will have completely normal testing, and the majority of these issues are rare, we can prevent many complications of pregnancy by testing early. It is important to remember that you can be asymptomatic for some of the conditions we test for too. And in some cases, finding these can be lifesaving for you and your baby. Here is the list of things that we test for and why.

Blood type with antibody screen: your blood type tells us whether it is possible for you and baby to be incompatible. If you have a “negative” blood type (such as A negative or O negative), and your baby’s blood type is positive, you could create antibodies if your blood mixes. This is why you need Rhogam shots when Rh negative. If you already have antibodies, which is really rare, we can let you know if you need additional testing to check on the health of the baby throughout the pregnancy, as these antibodies can lead to miscarriage in certain cases.

Complete blood count: we can check for anemia, platelet levels, inflammatory cells, and many other potential concerns with this test.

RPR: this stands for “rapid plasma reagin” and it is a test for an antibody to the bacteria that causes syphilis. If this is positive, you may have or previously had syphilis. Syphilis can be asymptomatic in some cases, and can be very dangerous for the baby if you have it. Fortunately, it is extremely easy to treat and we can treat it safely while you are pregnant.

Hepatitis B surface antigen: this is a test for hepatitis B infection in mom. If it is positive, you may not have known, but it could infect a new baby. If we know about this in advance, we will be able to minimize the chance of the baby getting the infection at birth.

Hepatitis C antibody: this is another sometimes asymptomatic blood infection that could be passed to your baby.

HIV antibody: HIV is asymptomatic in the early stages, so it would be important to know if you had an asymptomatic infection since your immune system diminishes in pregnancy. If HIV is active enough, you could pass HIV to your baby.

Gonorrhea and chlamydia: these common STIs are often asymptomatic, and they can cause severe infant infections. It is therefore really important to treat as soon as possible, ideally before baby is born.

Rubella antibody: if this level is low, you might be susceptible to measles, which increases risk of miscarriage in pregnancy. We have seen some outbreaks recently in the US, so it will be helpful to have your baseline immunity. We recommend avoiding areas of outbreak in general, but especially with low immunity. If it is low, we also recommend getting the MMR shot after you have the baby to prevent measles, mumps, and rubella, because you cannot get this vaccine while pregnant, and protecting yourself against these serious infections will protect your newborn baby until they can be vaccinated safely.

1 hour glucola: everyone’s favorite test in pregnancy! We sometimes do this more than once, but everyone needs to have it at the beginning of the third trimester to check for diabetes, which is asymptomatic for you, but can affect the baby’s growth and development. We will give you a sugary drink which raises your blood sugar and test your glucose level an hour later.

Thyroid stimulating hormone: we recommend checking your thyroid function, because it is important to treat thyroid disease in pregnancy if it is present, and it is sometimes asymptomatic.

Urine culture: we treat all UTIs when you are pregnant, due to the risk of preterm delivery, even with an asymptomatic urinary infection.

Pap: if you are 21 or older and haven’t had a pap recently, you may need an updated one. This test checks for changes in cervical cells which happen due to HPV infection.

These are the basics, but your doctor may recommend additional tests if there are other concerns or risk factors. You can always ask us any questions about these when we meet with you!


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