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Immunology & Autoimmune
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Currently under review
Pending specialist review and validation.
This test measures the number of lymphocytes in a sample of your baby's umbilical cord blood collected at birth. Lymphocytes are white blood cells that help fight infections and are made up of different types, including T cells, B cells, and natural killer cells. The count is generated by an automated hematology analyzer as part of a complete blood count with differential.
Because the sample is taken from the cord immediately after delivery, the result reflects your baby's circulating immune cells at that moment. It provides an early snapshot of immune status before the usual postnatal changes that happen in the first hours and days of life.
Doctors use this test to assess how ready your baby's immune system is to respond to infection and to look for signs of illness around the time of birth. It may be ordered if there are concerns about infection, inflammation, or if your baby has symptoms, was born preterm, or has risk factors for immune problems.
Lymphocyte counts that are higher or lower than expected can be related to stress during delivery, viral illnesses, or, less commonly, inherited immune conditions. Knowing this value can help your care team decide on further testing or monitoring and compare cord blood results with samples drawn after birth.
Your baby's healthcare provider will interpret this result together with gestational age, timing of cord clamping, type of delivery, and any maternal medications. Cord blood values can differ from blood taken from your baby later, so a repeat test from a peripheral vein is sometimes recommended for confirmation.
If the count appears lower than expected, your team may repeat the complete blood count, review a blood smear, or order tests that look at specific lymphocyte subsets to better understand T cells, B cells, and natural killer cells. If the count appears higher than expected, the team will consider infection, inflammation, or stress and may focus on clinical observation if your baby is otherwise well.
Your provider can explain what the result means for your baby and whether any follow-up, such as additional blood tests or specialist referral, is appropriate.
Reference intervals vary by laboratory, analyzer, methodology, population, and units. The ranges shown here are for education only. Always interpret your results against the reference interval printed on your own lab report.
Delayed or early cord clamping can change blood volume entering the newborn, which may slightly shift measured cell concentrations in the cord sample.
Clotting, insufficient mixing with anticoagulant, or delays before analysis can lead to unreliable automated counts and may falsely lower or raise results.
Preterm birth, induced labor, or cesarean versus vaginal delivery can influence stress responses and result in transient changes in white blood cell counts.
Corticosteroids, beta-agonists, magnesium sulfate, and other perinatal treatments can shift leukocyte distributions and affect newborn lymphocyte counts.
Infections around delivery or significant fetal stress can alter lymphocyte trafficking and redistribution, impacting the measured count in cord blood.
Growth restriction, twin gestation, or placental issues can affect blood volume and cell counts, leading to values that differ from typical expectations.
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