Necessary Laboratory Assessments for Infants Exposed to Maternal Alloantibodies

Please note that these are minimums and the exact timing of tests will be at the physician's discretion. Some infants will need labs more frequently, but medical literature states that all affected infants need a weekly hemoglobin/hematocrit check until approximately 12 weeks old to check for delayed onset anemia 1. Anemia may be present without visible signs and can develop in infants who were not anemic in the hospital - blood tests are essential. When possible, use microtesting as anemia may be worsened by repeated testing. Multiple articles state not to give iron supplements without first testing the ferritin level. Infants with HDFN do not suffer from iron-deficiency anemia, but hemolytic anemia instead. In one study none of the infants with HDFN were found to be iron deficient, and that 70% of them suffered from iron overload instead 2. Inappropriately administered iron supplements can be dangerous 2, 6. For additional information about any of the topics listed here, see the Additional Reading by Topic page.


These tests are from umbilical cord blood. If the cord blood clots, it needs to be redrawn as soon as possible 3, 5.


0-1 Week Old (Days 1-7)

  • Bilirubin - checked every 4, 6 or 12 hours in the hospital 3, 4.
  • Bilirubin - checked daily when out of the hospital. This is especially important during days 4-6 when bilirubin due to alloimmunization tends to peak.
  • Hemoglobin, or hematocrit 1 - usually checked at least 1 other time this week besides birth.
  • Reticulocyte count (retic)1

1-2 Weeks Old


3 Weeks Old


4 Weeks Old - 12 Weeks Old

  • Hemoglobin, or hematocrit - checked weekly 3. This is especially important for weeks four to six when newborns have a normal drop in hemoglobin. Infants suffering from HDFN can have a larger drop than normal and need their first transfusions during this window. This is not limited to infants whose mothers have had IUTs, but applies to all infants affected by alloimmunization. All affected infants need a weekly check until 12 weeks old or the hemoglobin is increasing for two to three weeks in a row.
  • Reticulocyte count (retic) - checked weekly (timing optional, but it is not necessary to check more often than weekly) to see if the infant is making new blood.
  • Other Tests - the neutrophil count and the thrombocyte/platelet count count may be repeated every two to four weeks if needed. Thrombocytopenia and neutropenia, are both common side effects of Hemolytic Disease of the Newborn1. Neutropenia may last for up to 1 year in some cases.

  1. Hemolytic disease of the fetus and newborn: managing the mother, fetus, and newborn.Delaney M, Matthews DC. Hematology Am Soc Hematol Educ Program. 2015;2015:146-51. doi: 10.1182/asheducation-2015.1.146.
  2. Rath ME, Smits-Wintjens VE, Oepkes D, Walther FJ, Lopriore E. Iron status in infants with alloimmune haemolytic disease in the first three months of life. Vox Sang. 2013 Nov;105(4):328-33. doi: 10.1111/vox.12061.
  3. Moise, K Jr. Post-Natal Management of Red Cell Alloimmunization Following IUT. Accessed September 20, 2017.
  4. Management of Hyperbilirubinemia in the Newborn Infant 35 or More Weeks of GestationPediatrics Jul 2004, 114 (1) 297-316; DOI: 10.1542/peds.114.1.2975.
  5. Murray N, Roberts IAG. Haemolytic Disease of the Newborn. Arch Dis Child Fetal Neonatal Ed. 2007 Mar; 92(2): F83–F88. doi: 10.1136/adc.2005.076794.
  6. Medscape. Schick, Paul. Hemolytic Anemia Treatment & Management. Accessed August 8, 2018.
  7. Calhoun, D. Postnatal diagnosis and management of hemolytic disease of the fetus and newborn. Accessed July 11, 2018.
  8. Demircioğlu F, Çağlayan Sözmen Ş, Yılmaz Ş, et al. Severe iron overload and hyporegenerative anemia in a case with rhesus hemolytic disease: therapeutic approach to rare complications. Rhesus hemolitik hastalıklı bir vakada hiporejeneratif anemi ve aşırı demir yüklenmesi: Nadir gelişen komplikasyona terapötik yaklaşım. Turk J Haematol. 2010;27(3):204–208. doi:10.5152/tjh.2010.30.