Transient Hypogammaglobulinemia of Infancy
Medically reviewed by Dr. Michael Okonkwo, MD, FAAP · Board-Certified Neonatologist
Content reviewed against published AAP, NIH, UpToDate guidelines
Last reviewed:
If your baby has been diagnosed with or you suspect transient hypogammaglobulinemia of infancy, here is what the evidence says.
The short answer
Transient hypogammaglobulinemia of infancy (THI) is a condition where a baby's immunoglobulin (antibody) levels — particularly IgG — drop lower than expected during the normal transition between losing maternal antibodies and producing their own. This physiologic dip normally occurs around 3-6 months of age, but in THI it is more pronounced or prolonged. Most children with THI are either asymptomatic or have mildly increased infections and outgrow the condition by age 2-4 years as their own antibody production matures. THI is generally benign and is not a true primary immunodeficiency.
Key takeaways
- Transient hypogammaglobulinemia of infancy (THI) is a condition where a baby's immunoglobulin (antibody) levels — particularly IgG — drop lower than expected during the normal transition between losing maternal antibodies and producing their own. This physiologic dip normally occurs around 3-6 months of age, but in THI it is more pronounced or prolonged. Most children with THI are either asymptomatic or have mildly increased infections and outgrow the condition by age 2-4 years as their own antibody production matures. THI is generally benign and is not a true primary immunodeficiency.
- Usually normal when: Your baby has low IgG levels at 3-6 months of age — this physiologic dip is expected in all infants
- Call your doctor if: Your baby with low immunoglobulin levels develops a severe infection (pneumonia requiring hospitalization, sepsis, or meningitis) — this could indicate a more serious immunodeficiency than THI
- Varies by age — see the age-by-age breakdown below
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What Parents Should Know
According to AAP, NIH, UpToDate guidelines, transient hypogammaglobulinemia of infancy (THI) is a condition where a baby's immunoglobulin (antibody) levels — particularly IgG — drop lower than expected during the normal transition between losing maternal antibodies and producing their own. This physiologic dip normally occurs around 3-6 months of age, but in THI it is more pronounced or prolonged. Most children with THI are either asymptomatic or have mildly increased infections and outgrow the condition by age 2-4 years as their own antibody production matures. THI is generally benign and is not a true primary immunodeficiency. At 0-6 months, all babies experience a natural decline in IgG levels as the maternal antibodies they received in the womb are broken down and before their own antibody production ramps up. This normal "physiologic nadir" occurs around 3-6 months. In THI, antibody levels dip lower than typical. Most babies at this age are still well-protected by breastmilk antibodies if breastfeeding. THI is often discovered incidentally when immune testing is done for other reasons. It is generally considered normal when your baby has low IgG levels at 3-6 months of age — this physiologic dip is expected in all infants. However, you should contact your pediatrician promptly if your baby with low immunoglobulin levels develops a severe infection (pneumonia requiring hospitalization, sepsis, or meningitis) — this could indicate a more serious immunodeficiency than THI.
Normal vs. Concerning
By Age
What to expect by age
0-6 months
All babies experience a natural decline in IgG levels as the maternal antibodies they received in the womb are broken down and before their own antibody production ramps up. This normal "physiologic nadir" occurs around 3-6 months. In THI, antibody levels dip lower than typical. Most babies at this age are still well-protected by breastmilk antibodies if breastfeeding. THI is often discovered incidentally when immune testing is done for other reasons.
6-12 months
This is the age when THI is most commonly diagnosed, as the baby's own IgG production has not yet compensated for the loss of maternal antibodies. Some babies with THI experience more frequent upper respiratory infections or ear infections, but many remain asymptomatic. Your pediatrician or immunologist will monitor immunoglobulin levels over time. It is important to distinguish THI from more serious primary immunodeficiencies — in THI, the baby's immune system responds normally to vaccines and has normal T-cell function.
1-3 years
Most children with THI see their immunoglobulin levels gradually normalize during this period. Antibody levels are typically rechecked every 6-12 months. If levels are normalizing and the child is not having serious infections, no treatment is needed. Rarely, a child with THI may need prophylactic antibiotics during winter months if recurrent infections are frequent. The vast majority of children outgrow THI by age 2-4 without any long-term immune problems.
3+ years
By this age, most children who had THI have fully normal immunoglobulin levels. If antibody levels remain significantly low beyond age 4, your immunologist will reassess for a more permanent immunodeficiency such as common variable immunodeficiency (CVID) or specific antibody deficiency. However, this progression is uncommon. Children who have normalized their immune function do not need ongoing monitoring.
What to Tell Your Pediatrician
- Describe when you first noticed transient hypogammaglobulinemia of infancy and how it has changed over time.
- Note your baby's current age and which age-specific patterns you are seeing.
- Mention if your baby has been diagnosed with low immunoglobulin levels and you want to understand what this means.
- Mention if your baby with THI seems to be getting more frequent infections than peers, especially ear infections, sinusitis, or bronchitis.
- 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
- Your baby has low IgG levels at 3-6 months of age — this physiologic dip is expected in all infants
- Your baby with THI is growing well, meeting milestones, and recovering from infections normally
- Your child's immunoglobulin levels are gradually trending upward on follow-up testing
- Your child with THI responds normally to vaccinations when tested
- Your baby has been diagnosed with low immunoglobulin levels and you want to understand what this means
- Your baby with THI seems to be getting more frequent infections than peers, especially ear infections, sinusitis, or bronchitis
- Immunoglobulin levels are not improving on follow-up testing after age 2
- Your baby with low immunoglobulin levels develops a severe infection (pneumonia requiring hospitalization, sepsis, or meningitis) — this could indicate a more serious immunodeficiency than THI
- Your baby with low antibody levels has chronic diarrhea, failure to thrive, or recurrent infections with unusual organisms — these suggest a more significant immune problem requiring urgent immunology evaluation
What You Can Do at Home
- Keep track of when you notice transient hypogammaglobulinemia of infancy — noting the time of day, duration, and any triggers can help your pediatrician.
- Remember that your baby has low IgG levels at 3-6 months of age — this physiologic dip is expected in all infants — 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 baby with low immunoglobulin levels develops a severe infection (pneumonia requiring hospitalization, sepsis, or meningitis) — this could indicate a more serious immunodeficiency than THI.
Related Conditions
Signs of Primary Immunodeficiency in Babies
Primary immunodeficiency disorders are conditions where the immune system does not function properly from birth. Warning signs include 4 or more new ear infections in a year, 2 or more serious sinus infections in a year, 2 or more months on antibiotics with little effect, 2 or more pneumonias in a year, failure to thrive, recurrent deep skin or organ abscesses, and a family history of primary immunodeficiency. These conditions are rare but treatable when identified early.
Warning Signs of Primary Immunodeficiency in Children
Primary immunodeficiency diseases (PIDs) are a group of over 450 genetic conditions where the immune system does not function properly. The Jeffrey Modell Foundation has identified 10 warning signs in children: 4+ new ear infections in a year, 2+ serious sinus infections in a year, 2+ months on antibiotics with little effect, 2+ pneumonias in a year, failure to gain weight or grow normally, recurrent deep skin or organ abscesses, persistent thrush in mouth or fungal infection on skin, need for IV antibiotics to clear infections, 2+ deep-seated infections (sepsis, meningitis), and a family history of PID. If your child meets 2 or more of these criteria, discuss immunologic testing with your pediatrician.
Selective IgA Deficiency in Children
Selective IgA deficiency is the most common primary immunodeficiency, affecting about 1 in 300-700 people. IgA is the main antibody found in mucous membranes (respiratory tract, gut, saliva, tears) and is the first line of defense against infections at these surfaces. Many people with IgA deficiency are completely asymptomatic and never diagnosed. Others experience more frequent respiratory or gastrointestinal infections, increased allergies, or associated autoimmune conditions. There is no replacement therapy for IgA specifically, but most children with IgA deficiency do well with supportive care.
How Often Do Babies Get Sick? What's Normal
It is normal for babies and toddlers to get 6-8 upper respiratory infections (colds) per year, and children in daycare may have even more — up to 8-12 illnesses annually. According to the AAP, the average child will have experienced 80-100 viral infections by their 6th birthday. Babies in group childcare settings tend to get sick more frequently in their first 1-2 years (often called the "germ year") but research shows they have fewer infections in later childhood compared to children who were not in early group care, as their immune systems were exposed sooner. Each cold typically lasts 7-10 days, and with back-to-back infections, it can feel like your baby is sick continuously through the fall and winter months. This frequent illness, while exhausting for families, is a normal part of immune system development.
Related Resources
Frequently asked questions
Is transient hypogammaglobulinemia of infancy normal?
When should I call the doctor about transient hypogammaglobulinemia of infancy?
When is transient hypogammaglobulinemia of infancy normal?
What causes transient hypogammaglobulinemia of infancy?
What should I mention to my pediatrician about transient hypogammaglobulinemia of infancy?
Is transient hypogammaglobulinemia of infancy normal at 0-6 months?
Is transient hypogammaglobulinemia of infancy normal at 6-12 months?
Should I go to the ER for transient hypogammaglobulinemia of infancy?
Does transient hypogammaglobulinemia of infancy go away on its own?
References
Doctor Visit Checklist
Bring this checklist to your next pediatrician visit to discuss Transient Hypogammaglobulinemia of Infancy.
Things to mention
- Describe when you first noticed transient hypogammaglobulinemia of infancy and how it has changed over time.
- Note your baby's current age and which age-specific patterns you are seeing.
- Mention if your baby has been diagnosed with low immunoglobulin levels and you want to understand what this means.
- Mention if your baby with THI seems to be getting more frequent infections than peers, especially ear infections, sinusitis, or bronchitis.
- 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 baby has been diagnosed with low immunoglobulin levels and you want to understand what this means
- Your baby with THI seems to be getting more frequent infections than peers, especially ear infections, sinusitis, or bronchitis
- Immunoglobulin levels are not improving on follow-up testing after age 2
Urgent signs to report immediately
- Your baby with low immunoglobulin levels develops a severe infection (pneumonia requiring hospitalization, sepsis, or meningitis) — this could indicate a more serious immunodeficiency than THI
- Your baby with low antibody levels has chronic diarrhea, failure to thrive, or recurrent infections with unusual organisms — these suggest a more significant immune problem requiring urgent immunology evaluation
My notes
From ismybabyalright.com — free, evidence-based baby health guides
All content follows our editorial policy and is reviewed against published clinical guidelines.
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Related Resources
Bottom line
Most cases of transient hypogammaglobulinemia of infancy are normal. Talk to your pediatrician if your baby with low immunoglobulin levels develops a severe infection (pneumonia requiring hospitalization, sepsis, or meningitis) — this could indicate a more serious immunodeficiency than thi.
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
Signs of Primary Immunodeficiency in Babies
Primary immunodeficiency disorders are conditions where the immune system does not function properly from birth. Warning signs include 4 or more new ear infections in a year, 2 or more serious sinus infections in a year, 2 or more months on antibiotics with little effect, 2 or more pneumonias in a year, failure to thrive, recurrent deep skin or organ abscesses, and a family history of primary immunodeficiency. These conditions are rare but treatable when identified early.
Warning Signs of Primary Immunodeficiency in Children
Primary immunodeficiency diseases (PIDs) are a group of over 450 genetic conditions where the immune system does not function properly. The Jeffrey Modell Foundation has identified 10 warning signs in children: 4+ new ear infections in a year, 2+ serious sinus infections in a year, 2+ months on antibiotics with little effect, 2+ pneumonias in a year, failure to gain weight or grow normally, recurrent deep skin or organ abscesses, persistent thrush in mouth or fungal infection on skin, need for IV antibiotics to clear infections, 2+ deep-seated infections (sepsis, meningitis), and a family history of PID. If your child meets 2 or more of these criteria, discuss immunologic testing with your pediatrician.
Selective IgA Deficiency in Children
Selective IgA deficiency is the most common primary immunodeficiency, affecting about 1 in 300-700 people. IgA is the main antibody found in mucous membranes (respiratory tract, gut, saliva, tears) and is the first line of defense against infections at these surfaces. Many people with IgA deficiency are completely asymptomatic and never diagnosed. Others experience more frequent respiratory or gastrointestinal infections, increased allergies, or associated autoimmune conditions. There is no replacement therapy for IgA specifically, but most children with IgA deficiency do well with supportive care.
How Often Do Babies Get Sick? What's Normal
It is normal for babies and toddlers to get 6-8 upper respiratory infections (colds) per year, and children in daycare may have even more — up to 8-12 illnesses annually. According to the AAP, the average child will have experienced 80-100 viral infections by their 6th birthday. Babies in group childcare settings tend to get sick more frequently in their first 1-2 years (often called the "germ year") but research shows they have fewer infections in later childhood compared to children who were not in early group care, as their immune systems were exposed sooner. Each cold typically lasts 7-10 days, and with back-to-back infections, it can feel like your baby is sick continuously through the fall and winter months. This frequent illness, while exhausting for families, is a normal part of immune system development.
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.
Achondroplasia (Dwarfism) in Babies
Achondroplasia is the most common form of short-limbed dwarfism, affecting about 1 in 15,000 to 40,000 births. It is caused by a mutation in the FGFR3 gene and is usually apparent at birth with characteristic features including short limbs, a larger head, and a prominent forehead. Intelligence is normal. With monitoring for specific complications and supportive care, children with achondroplasia lead full, active, and independent lives.