Medical Conditions

Autoimmune Neutropenia of Infancy - Low White Blood Cell Count

Medically reviewed by Dr. Michael Okonkwo, MD, FAAP · Board-Certified Neonatologist

Content reviewed against published AAP, ASH, NIH guidelines

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If your baby has been diagnosed with or you suspect autoimmune neutropenia of infancy - low white blood cell count, here is what the evidence says.

The short answer

Autoimmune neutropenia of infancy (AIN) is the most common cause of chronic neutropenia (low neutrophil count) in children under 2 years old. The body makes antibodies against its own neutrophils (a type of white blood cell that fights bacterial infections), causing their count to drop. Despite the sometimes very low neutrophil numbers, most children with AIN have surprisingly mild clinical courses with only minor infections such as ear infections or skin infections. AIN typically resolves on its own by age 2 to 4 years and rarely requires treatment.

Key takeaways

  • Autoimmune neutropenia of infancy (AIN) is the most common cause of chronic neutropenia (low neutrophil count) in children under 2 years old. The body makes antibodies against its own neutrophils (a type of white blood cell that fights bacterial infections), causing their count to drop. Despite the sometimes very low neutrophil numbers, most children with AIN have surprisingly mild clinical courses with only minor infections such as ear infections or skin infections. AIN typically resolves on its own by age 2 to 4 years and rarely requires treatment.
  • Usually normal when: Your child has a low neutrophil count discovered incidentally but is otherwise healthy and growing well
  • Call your doctor if: Your child with known neutropenia develops a fever of 100.4F (38C) or higher, as fever with neutropenia can indicate a serious bacterial infection that requires prompt medical evaluation and may need IV antibiotics
  • Varies by age — see the age-by-age breakdown below
“Fever itself is not an illness — rather, it is a sign or symptom that the body is fighting an infection. Fever stimulates certain defenses, such as the white blood cells, which attack and destroy invading bacteria.”
— Fever and Your Child, American Academy of Pediatrics (AAP)

This is one of the most common questions parents ask. Searching for answers means you care.

What Parents Should Know

According to AAP, ASH, NIH guidelines, autoimmune neutropenia of infancy (AIN) is the most common cause of chronic neutropenia (low neutrophil count) in children under 2 years old. The body makes antibodies against its own neutrophils (a type of white blood cell that fights bacterial infections), causing their count to drop. Despite the sometimes very low neutrophil numbers, most children with AIN have surprisingly mild clinical courses with only minor infections such as ear infections or skin infections. AIN typically resolves on its own by age 2 to 4 years and rarely requires treatment. At 0-6 months, aIN is most commonly diagnosed between 5 and 15 months of age, but can occasionally be identified earlier when a blood test done for another reason reveals a very low absolute neutrophil count (ANC), often below 500 cells per microliter. In newborns, other causes of neutropenia such as neonatal alloimmune neutropenia (from maternal antibodies), sepsis, or congenital neutropenia syndromes should be considered first. If your baby has an isolated low neutrophil count but appears well and is gaining weight, your pediatrician may monitor with repeat blood counts before pursuing further workup. It is generally considered normal when your child has a low neutrophil count discovered incidentally but is otherwise healthy and growing well. However, you should contact your pediatrician promptly if your child with known neutropenia develops a fever of 100.4F (38C) or higher, as fever with neutropenia can indicate a serious bacterial infection that requires prompt medical evaluation and may need IV antibiotics.

Sources: [1], [2], [3]

Normal vs. Concerning

Usually Normal
Worth Discussing
Your child has a low neutrophil count discovered incidentally but is otherwise healthy and growing well
Your child with known neutropenia develops a fever of 100.4F (38C) or higher, as fever with neutropenia can indicate a serious bacterial infection that requires prompt medical evaluation and may need IV antibiotics
Your child has AIN and experiences only mild infections such as occasional ear infections or skin infections that respond to standard antibiotics
Your child appears very ill with signs of sepsis such as high fever, rapid breathing, lethargy, mottled skin, or poor responsiveness, requiring emergency care
The neutrophil count fluctuates between low and near-normal levels over time
Your child with known AIN seems to be getting more frequent infections than before
Your child with known AIN is active, eating well, and meeting developmental milestones
You notice mouth sores (stomatitis) or recurring skin infections or abscesses

By Age

What to expect by age

0-6 months

AIN is most commonly diagnosed between 5 and 15 months of age, but can occasionally be identified earlier when a blood test done for another reason reveals a very low absolute neutrophil count (ANC), often below 500 cells per microliter. In newborns, other causes of neutropenia such as neonatal alloimmune neutropenia (from maternal antibodies), sepsis, or congenital neutropenia syndromes should be considered first. If your baby has an isolated low neutrophil count but appears well and is gaining weight, your pediatrician may monitor with repeat blood counts before pursuing further workup.

6-12 months

This is the peak age of diagnosis for AIN. Parents typically learn about the condition when routine blood work or blood tests during an illness reveal a very low ANC. Despite the alarming numbers (sometimes below 200), children with AIN are often surprisingly well. They may have slightly more frequent ear infections, upper respiratory infections, or skin infections than peers, but serious invasive bacterial infections (sepsis, pneumonia, meningitis) are rare. Anti-neutrophil antibodies can be detected in the blood, confirming the autoimmune cause. Bone marrow examination is generally not needed if the clinical picture is consistent with AIN.

1-2 years

During this period, the neutrophil count often fluctuates, with some counts showing near-normal levels and others being very low. This variability is characteristic of AIN and helps distinguish it from more serious congenital neutropenia syndromes, where counts are consistently very low. Most children with AIN do not require any specific treatment. If your child develops a bacterial infection, standard antibiotics are effective. In rare cases of severe infection, G-CSF (granulocyte colony-stimulating factor) can be given to temporarily boost neutrophil production. Your hematologist will typically check blood counts every 1-3 months.

2-4 years

The majority of children with AIN experience spontaneous resolution by age 2 to 4 years, with neutrophil counts gradually normalizing as the autoantibodies disappear. About 95% of cases resolve by age 5. Once neutrophil counts have been consistently normal for several months, monitoring can be discontinued. In the rare cases where neutropenia persists beyond age 5, further evaluation may be needed to rule out other causes. Children who have recovered from AIN have no long-term consequences and do not have increased risk of recurrence or other autoimmune conditions.

What to Tell Your Pediatrician

  • Describe when you first noticed autoimmune neutropenia of infancy - low white blood cell count and how it has changed over time.
  • Note your baby's current age and which age-specific patterns you are seeing.
  • Mention if your child with known AIN seems to be getting more frequent infections than before.
  • Mention if you notice mouth sores (stomatitis) or recurring skin infections or abscesses.
  • Let your doctor know if you have noticed any related concerns, such as changes in feeding, sleep, or movement patterns.
  • Bring a list of any questions or observations you want to discuss at the appointment.

What Should You Do?

When to take action

Probably normal when...
  • Your child has a low neutrophil count discovered incidentally but is otherwise healthy and growing well
  • Your child has AIN and experiences only mild infections such as occasional ear infections or skin infections that respond to standard antibiotics
  • The neutrophil count fluctuates between low and near-normal levels over time
  • Your child with known AIN is active, eating well, and meeting developmental milestones
  • The neutrophil count is gradually improving over months as expected with the natural course of AIN
Mention at your next visit when...
  • Your child with known AIN seems to be getting more frequent infections than before
  • You notice mouth sores (stomatitis) or recurring skin infections or abscesses
  • The neutropenia has persisted beyond age 4-5 years without improvement
Act now when...
  • Your child with known neutropenia develops a fever of 100.4F (38C) or higher, as fever with neutropenia can indicate a serious bacterial infection that requires prompt medical evaluation and may need IV antibiotics
  • Your child appears very ill with signs of sepsis such as high fever, rapid breathing, lethargy, mottled skin, or poor responsiveness, requiring emergency care

What You Can Do at Home

  • Keep track of when you notice autoimmune neutropenia of infancy - low white blood cell count — noting the time of day, duration, and any triggers can help your pediatrician.
  • Remember that your child has a low neutrophil count discovered incidentally but is otherwise healthy and growing well — this is generally within the range of normal.
  • At 0-6 months, focus on observation rather than intervention unless your pediatrician advises otherwise.
  • Follow any care instructions from your pediatrician. Keep a written log of symptoms to bring to appointments.
  • While monitoring at home, seek immediate care if your child with known neutropenia develops a fever of 100.4F (38C) or higher, as fever with neutropenia can indicate a serious bacterial infection that requires prompt medical evaluation and may need IV antibiotics.

My Baby Looks Very Pale

Babies' skin color can vary naturally depending on temperature, activity, and genetics. However, true pallor (unusual paleness of the skin, lips, or nail beds) can sometimes indicate anemia, poor circulation, or an infection. If your baby looks noticeably paler than usual, especially in the lips, gums, inner eyelids, or palms, it is worth mentioning to your pediatrician.

Baby Bruises Easily - When to Worry

Bruising in babies and toddlers is extremely common once they become mobile. Shins, forehead, knees, and elbows are the most typical locations, matching where active children bump into things. Bruising in these "bony prominence" areas is expected and normal. Bruising becomes more concerning when it appears in unusual locations (torso, back, cheeks, neck, buttocks), in a baby who is not yet mobile, or when bruises appear without any known injury. In these cases, your pediatrician may recommend bloodwork to check for bleeding disorders.

Petechiae (Tiny Red Dots) on My Baby

Petechiae are tiny red, purple, or brown dots caused by broken blood vessels just under the skin. While they can appear after vigorous crying, coughing, or vomiting in healthy babies, they can also signal serious conditions. Always contact your pediatrician if you notice petechiae, especially if they appear suddenly or are widespread.

Signs of Aplastic Anemia in Babies

Aplastic anemia is a rare condition where the bone marrow fails to produce enough blood cells (red cells, white cells, and platelets). Signs include fatigue and pallor (low red cells), frequent or severe infections (low white cells), and easy bruising or bleeding (low platelets). It can be inherited (Fanconi anemia, Diamond-Blackfan anemia) or acquired. Early diagnosis by a pediatric hematologist is essential for treatment, which may include medications, blood transfusions, or bone marrow transplant.

Milestone

Month-by-Month Development

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Guide

When to Call the Doctor

General guide on when to call the pediatrician, visit urgent care, or go to the ER.

Frequently asked questions

Is autoimmune neutropenia of infancy - low white blood cell count normal?
Autoimmune neutropenia of infancy (AIN) is the most common cause of chronic neutropenia (low neutrophil count) in children under 2 years old. The body makes antibodies against its own neutrophils (a type of white blood cell that fights bacterial infections), causing their count to drop. Despite the sometimes very low neutrophil numbers, most children with AIN have surprisingly mild clinical courses with only minor infections such as ear infections or skin infections. AIN typically resolves on its own by age 2 to 4 years and rarely requires treatment.
When should I call the doctor about autoimmune neutropenia of infancy - low white blood cell count?
Your child with known neutropenia develops a fever of 100.4F (38C) or higher, as fever with neutropenia can indicate a serious bacterial infection that requires prompt medical evaluation and may need IV antibiotics Your child appears very ill with signs of sepsis such as high fever, rapid breathing, lethargy, mottled skin, or poor responsiveness, requiring emergency care
When is autoimmune neutropenia of infancy - low white blood cell count normal?
Your child has a low neutrophil count discovered incidentally but is otherwise healthy and growing well Your child has AIN and experiences only mild infections such as occasional ear infections or skin infections that respond to standard antibiotics The neutrophil count fluctuates between low and near-normal levels over time
What causes autoimmune neutropenia of infancy - low white blood cell count?
Autoimmune neutropenia of infancy (AIN) is the most common cause of chronic neutropenia (low neutrophil count) in children under 2 years old. The body makes antibodies against its own neutrophils (a type of white blood cell that fights bacterial infections), causing their count to drop. Despite the sometimes very low neutrophil numbers, most children with AIN have surprisingly mild clinical courses with only minor infections such as ear infections or skin infections. AIN typically resolves on its own by age 2 to 4 years and rarely requires treatment. Common explanations include: Your child has a low neutrophil count discovered incidentally but is otherwise healthy and growing well. Your child has AIN and experiences only mild infections such as occasional ear infections or skin infections that respond to standard antibiotics.
What should I mention to my pediatrician about autoimmune neutropenia of infancy - low white blood cell count?
You should mention autoimmune neutropenia of infancy - low white blood cell count at your next visit if: Your child with known AIN seems to be getting more frequent infections than before. You notice mouth sores (stomatitis) or recurring skin infections or abscesses. The neutropenia has persisted beyond age 4-5 years without improvement.
Is autoimmune neutropenia of infancy - low white blood cell count normal at 0-6 months?
AIN is most commonly diagnosed between 5 and 15 months of age, but can occasionally be identified earlier when a blood test done for another reason reveals a very low absolute neutrophil count (ANC), often below 500 cells per microliter. In newborns, other causes of neutropenia such as neonatal alloimmune neutropenia (from maternal antibodies), sepsis, or congenital neutropenia syndromes should be considered first. If your baby has an isolated low neutrophil count but appears well and is gaining weight, your pediatrician may monitor with repeat blood counts before pursuing further workup.
Is autoimmune neutropenia of infancy - low white blood cell count normal at 6-12 months?
This is the peak age of diagnosis for AIN. Parents typically learn about the condition when routine blood work or blood tests during an illness reveal a very low ANC. Despite the alarming numbers (sometimes below 200), children with AIN are often surprisingly well. They may have slightly more frequent ear infections, upper respiratory infections, or skin infections than peers, but serious invasive bacterial infections (sepsis, pneumonia, meningitis) are rare. Anti-neutrophil antibodies can be detected in the blood, confirming the autoimmune cause. Bone marrow examination is generally not needed if the clinical picture is consistent with AIN.
Should I go to the ER for autoimmune neutropenia of infancy - low white blood cell count?
Seek emergency care if your child with known neutropenia develops a fever of 100.4F (38C) or higher, as fever with neutropenia can indicate a serious bacterial infection that requires prompt medical evaluation and may need IV antibiotics, or if your child appears very ill with signs of sepsis such as high fever, rapid breathing, lethargy, mottled skin, or poor responsiveness, requiring emergency care. When in doubt, call your pediatrician's after-hours line for guidance.
Does autoimmune neutropenia of infancy - low white blood cell count go away on its own?
In many cases, autoimmune neutropenia of infancy - low white blood cell count resolves on its own, especially when your child has a low neutrophil count discovered incidentally but is otherwise healthy and growing well. By 2-4 years, the majority of children with AIN experience spontaneous resolution by age 2 to 4 years, with neutrophil counts gradually normalizing as the autoantibodies disappear. About 95% of cases resolve by age 5. Once neutrophil counts have been consistently normal for several months, monitoring can be discontinued. In the rare cases where neutropenia persists beyond age 5, further evaluation may be needed to rule out other causes. Children who have recovered from AIN have no long-term consequences and do not have increased risk of recurrence or other autoimmune conditions.
AAPASHNIH

References

  1. [1]Boxer LA. How to Approach Neutropenia. Hematology ASH Education Program. 2012;2012(1):174-182. AAP
  2. [2]Bux J, Behrens G, Jaeger G, Welte K. Diagnosis and Clinical Course of Autoimmune Neutropenia in Infancy: Analysis of 240 Cases. Blood. 1998;91(1):181-186. ASH
  3. [3]MedlinePlus. Neutropenia. National Library of Medicine. NIH

Doctor Visit Checklist

Bring this checklist to your next pediatrician visit to discuss Autoimmune Neutropenia of Infancy - Low White Blood Cell Count.

Things to mention

  • Describe when you first noticed autoimmune neutropenia of infancy - low white blood cell count and how it has changed over time.
  • Note your baby's current age and which age-specific patterns you are seeing.
  • Mention if your child with known AIN seems to be getting more frequent infections than before.
  • Mention if you notice mouth sores (stomatitis) or recurring skin infections or abscesses.
  • Let your doctor know if you have noticed any related concerns, such as changes in feeding, sleep, or movement patterns.
  • Bring a list of any questions or observations you want to discuss at the appointment.

Observations to share

  • Your child with known AIN seems to be getting more frequent infections than before
  • You notice mouth sores (stomatitis) or recurring skin infections or abscesses
  • The neutropenia has persisted beyond age 4-5 years without improvement

Urgent signs to report immediately

  • Your child with known neutropenia develops a fever of 100.4F (38C) or higher, as fever with neutropenia can indicate a serious bacterial infection that requires prompt medical evaluation and may need IV antibiotics
  • Your child appears very ill with signs of sepsis such as high fever, rapid breathing, lethargy, mottled skin, or poor responsiveness, requiring emergency care

My notes

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Bottom line

Most cases of autoimmune neutropenia of infancy - low white blood cell count are normal. Talk to your pediatrician if your child with known neutropenia develops a fever of 100.4f (38c) or higher, as fever with neutropenia can indicate a serious bacterial infection that requires prompt medical evaluation and may need iv antibiotics.

Trust your instincts. If something feels wrong, reach out to your pediatrician. Worrying about your baby means you care — that is a good thing.

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Related Medical Concerns

My Baby Looks Very Pale

Babies' skin color can vary naturally depending on temperature, activity, and genetics. However, true pallor (unusual paleness of the skin, lips, or nail beds) can sometimes indicate anemia, poor circulation, or an infection. If your baby looks noticeably paler than usual, especially in the lips, gums, inner eyelids, or palms, it is worth mentioning to your pediatrician.

Baby Bruises Easily - When to Worry

Bruising in babies and toddlers is extremely common once they become mobile. Shins, forehead, knees, and elbows are the most typical locations, matching where active children bump into things. Bruising in these "bony prominence" areas is expected and normal. Bruising becomes more concerning when it appears in unusual locations (torso, back, cheeks, neck, buttocks), in a baby who is not yet mobile, or when bruises appear without any known injury. In these cases, your pediatrician may recommend bloodwork to check for bleeding disorders.

Petechiae (Tiny Red Dots) on My Baby

Petechiae are tiny red, purple, or brown dots caused by broken blood vessels just under the skin. While they can appear after vigorous crying, coughing, or vomiting in healthy babies, they can also signal serious conditions. Always contact your pediatrician if you notice petechiae, especially if they appear suddenly or are widespread.

Signs of Aplastic Anemia in Babies

Aplastic anemia is a rare condition where the bone marrow fails to produce enough blood cells (red cells, white cells, and platelets). Signs include fatigue and pallor (low red cells), frequent or severe infections (low white cells), and easy bruising or bleeding (low platelets). It can be inherited (Fanconi anemia, Diamond-Blackfan anemia) or acquired. Early diagnosis by a pediatric hematologist is essential for treatment, which may include medications, blood transfusions, or bone marrow transplant.

Fanconi Anemia Signs in My Baby

Fanconi anemia (FA) is a rare inherited bone marrow failure syndrome that causes progressive decline in blood cell production, physical anomalies, short stature, and increased cancer risk. About 75% of affected children have birth defects, most commonly involving the thumbs and forearms (radial ray anomalies), skin pigmentation changes, and short stature. Bone marrow failure typically develops between ages 5 and 10 but can occur earlier. Early diagnosis through genetic testing is important for monitoring, treatment planning, and cancer surveillance.

My Baby's Head Shape Looks Abnormal

Many babies develop temporary head shape irregularities that are completely normal. A cone-shaped head from vaginal delivery reshapes within days. Mild positional flattening (plagiocephaly) from sleeping on the back is very common and usually improves with repositioning and tummy time. However, head shape changes involving ridges, a persistently bulging fontanelle, or rapid head growth changes should be evaluated to rule out craniosynostosis.