Pregnancy and Prenatal Laboratory Testing

Content Review: May 2021 Last Update:

A variety of laboratory tests are recommended before and during pregnancy to screen for and diagnose conditions that may affect the mother and/or developing infant. Recommended testing includes carrier screening to determine the risk for heritable genetic disease, tests to screen for and diagnose chromosomal abnormalities in the fetus, and tests to monitor the health of both fetus and mother throughout the pregnancy.

 

Carrier Screening
for Genetic Disorders


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Prenatal Testing for Chromosomal Abnormalities and Neural Tube Defects


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Laboratory Testing

Carrier Screening for Genetic Disorders

Carrier screening can be performed before pregnancy to determine the risk of passing on heritable genetic disorders. There are many acceptable strategies for carrier screening, including targeted screening for specific conditions (based on ethnicity and family history) and expanded screening to detect multiple conditions simultaneously. Laboratory testing for carrier screening purposes may entail single-gene analysis, targeted variant panels, or expanded panels. For an in-depth discussion of carrier screening, including recommendations from professional societies, see the ARUP Consult Carrier Screening for Genetic Disorders topic.

Prenatal Testing for Chromosomal Abnormalities and Neural Tube Defects

Prenatal testing is offered to all pregnant women to identify pregnancies with a chromosomal disorder, such as trisomy 21 (Down syndrome) or an open neural tube defect (ONTD).    Most professional guidelines define prenatal genetic testing as encompassing two categories of testing: screening and diagnosis. Maternal serum screening (MSS) and cell-free DNA (cfDNA) screening estimate a patient’s risk of carrying a fetus with a chromosomal disorder.    For more detailed information, see the ARUP Consult Prenatal Testing for Chromosomal Abnormalities and Neural Tube Defects topic.

Testing for Hematologic Conditions in Pregnancy

Many serious hematologic disorders may affect the fetus, including hemolytic disease of the fetus and newborn and hemolytic anemias. For more information on the diagnosis of these conditions in pregnancy, see the ARUP Consult Hemolytic Disease of the Fetus and Newborn and Hemolytic Anemias topics.

Infectious Disease Testing During Pregnancy

Several common infectious diseases may adversely affect pregnancy. For example, toxoplasmosis (Toxoplasma gondii) is often asymptomatic in healthy adults, but may be serious in pregnant women. Refer to the ARUP Consult Toxoplasma gondii topic and Toxoplasmosis Serologic Testing for Pregnant Women Algorithm for more details.

Cytomegalovirus is another common infection that may lead to serious complications in pregnant women, although routine screening is not currently recommended. See the ARUP Consult Cytomegalovirus topic for additional information.

Infection with parvovirus B19 may lead to hemolytic disease in the fetus.

Other infections that may have an adverse effect during pregnancy include hepatitis B virus (HBV) and hepatitis C virus (HCV), rubella, Listeria monocytogenes, herpes simplex virus, HIV, Epstein-Barr virus (EBV), varicella-zoster virus, syphilis, group B Streptococcus, and enterovirus. See the following ARUP Consult topics for laboratory testing information:

For a discussion of infectious disease screening during pregnancy, see the Routine Testing During Pregnancy section.

Other Laboratory Testing During Pregnancy

Other tests may be used to monitor the pregnancy and to ensure the health of the mother and fetus.

Screening for Pregnancy

Human chorionic gonadotropin (hCG) testing is used to screen for pregnancy before some medical procedures or administration of medication that may harm a fetus.

Routine Testing During Pregnancy

Routine laboratory tests are performed to identify conditions that may increase the probability of complications during pregnancy. These tests include routine blood work (eg, CBC, blood typing, Rh factor), urinalysis, urine culture, and tests for specific diseases. For example, thyroid disease is common in pregnancy, and may affect outcomes. Furthermore, the thyroid gland undergoes several changes that complicate testing during pregnancy. For more information, see the ARUP Consult Thyroid Disease in Pregnancy topic.

Screening for gestational diabetes mellitus is recommended in pregnant women, as well as in women planning to become pregnant who are either overweight or have other risk factors. An early glucose screening can be performed, followed by an oral glucose tolerance test at 24-28 weeks of gestation.  For detailed information about diabetes testing in pregnancy, see the ARUP Consult Diabetes Mellitus topic.

Screening recommendations exist for the following infectious diseases during pregnancy :

 

Testing for Uncommon Conditions Related to Pregnancy

HELLP syndrome, which involves hemolysis, elevated liver function tests, and low platelet count, is a complication of preeclampsia and eclampsia that occurs in pregnant women.

Gestational trophoblastic tumors are tumors (benign or malignant) that arise from cells that would normally develop into the placenta during pregnancy. The ARUP Consult Gestational Trophoblastic Disease topic discusses the testing strategy for these conditions in detail.

Pemphigoid gestationis (herpes gestationis) is a rare disease of pregnancy and puerperium. Prompt, accurate diagnosis is essential for therapy planning to minimize morbidity and patient discomfort. Visit the ARUP Consult Pemphigoid Gestationis - Gestational Pemphigoid topic and Immunobullous Diseases Testing Algorithm - Pregnancy for more information.

Medical Experts

Contributor

Jackson

Brian R. Jackson, MD, MS
Brian R. Jackson, MD, MS
Adjunct Professor of Pathology and Biomedical Informatics, University of Utah
Medical Director, Business Development, ARUP Laboratories

References