Physiologic Anemia of Infancy - Normal Hemoglobin Drop
Medically reviewed by Dr. Michael Okonkwo, MD, FAAP · Board-Certified Neonatologist
Content reviewed against published AAP, AAP, NIH guidelines
Last reviewed:
If your baby has been diagnosed with or you suspect physiologic anemia of infancy - normal hemoglobin drop, here is what the evidence says.
The short answer
Physiologic anemia of infancy is a normal, expected drop in hemoglobin levels that occurs in all babies around 6 to 8 weeks of age. After birth, the baby transitions from fetal hemoglobin to adult hemoglobin, and red blood cell production temporarily decreases as the body adjusts to the oxygen-rich environment outside the womb. In full-term babies, hemoglobin typically drops to about 9.5-11 g/dL and then recovers on its own without treatment. In premature babies, the drop can be more pronounced (anemia of prematurity) and may occasionally require intervention.
Key takeaways
- Physiologic anemia of infancy is a normal, expected drop in hemoglobin levels that occurs in all babies around 6 to 8 weeks of age. After birth, the baby transitions from fetal hemoglobin to adult hemoglobin, and red blood cell production temporarily decreases as the body adjusts to the oxygen-rich environment outside the womb. In full-term babies, hemoglobin typically drops to about 9.5-11 g/dL and then recovers on its own without treatment. In premature babies, the drop can be more pronounced (anemia of prematurity) and may occasionally require intervention.
- Usually normal when: Your baby has mild anemia (hemoglobin 9.5-11 g/dL) around 6-8 weeks of age but is feeding well, active, and gaining weight
- Call your doctor if: Your baby at any age is very pale, breathing rapidly, has a fast heartbeat, is refusing feeds, or is lethargic, as this could indicate severe anemia requiring urgent evaluation and possible transfusion
- 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.”
Thousands of parents search for this exact thing. You are not alone.
What Parents Should Know
According to AAP, NIH guidelines, physiologic anemia of infancy is a normal, expected drop in hemoglobin levels that occurs in all babies around 6 to 8 weeks of age. After birth, the baby transitions from fetal hemoglobin to adult hemoglobin, and red blood cell production temporarily decreases as the body adjusts to the oxygen-rich environment outside the womb. In full-term babies, hemoglobin typically drops to about 9.5-11 g/dL and then recovers on its own without treatment. In premature babies, the drop can be more pronounced (anemia of prematurity) and may occasionally require intervention. At 0-2 weeks, at birth, babies have high hemoglobin levels (14-20 g/dL) because they needed extra red blood cells to carry oxygen in the lower-oxygen environment of the womb. After birth, the baby is now breathing oxygen-rich air, so the body signals the bone marrow to slow red blood cell production. The hormone erythropoietin drops significantly. This is the beginning of the normal transition. Delayed cord clamping at birth can provide additional iron stores and slightly higher initial hemoglobin levels. It is generally considered normal when your baby has mild anemia (hemoglobin 9.5-11 g/dL) around 6-8 weeks of age but is feeding well, active, and gaining weight. However, you should contact your pediatrician promptly if your baby at any age is very pale, breathing rapidly, has a fast heartbeat, is refusing feeds, or is lethargic, as this could indicate severe anemia requiring urgent evaluation and possible transfusion.
Normal vs. Concerning
By Age
What to expect by age
0-2 weeks
At birth, babies have high hemoglobin levels (14-20 g/dL) because they needed extra red blood cells to carry oxygen in the lower-oxygen environment of the womb. After birth, the baby is now breathing oxygen-rich air, so the body signals the bone marrow to slow red blood cell production. The hormone erythropoietin drops significantly. This is the beginning of the normal transition. Delayed cord clamping at birth can provide additional iron stores and slightly higher initial hemoglobin levels.
2-8 weeks
During this period, the hemoglobin gradually declines as older fetal red blood cells are broken down and new adult red blood cells are produced at a lower rate. The lowest point (nadir) typically occurs at 6-8 weeks of age in full-term babies, with hemoglobin dropping to approximately 9.5-11 g/dL. This is completely normal and does not require treatment. Your baby should still appear well, feed normally, and gain weight. In premature babies, the nadir occurs earlier (4-6 weeks), drops lower (7-9 g/dL or less), and may cause symptoms, sometimes requiring transfusion.
2-4 months
After the nadir, the bone marrow begins increasing red blood cell production in response to lower oxygen-carrying capacity. Hemoglobin levels gradually rise. If your full-term baby remains mildly pale but is feeding well, active, and gaining weight normally, the physiologic anemia is resolving as expected. However, if hemoglobin drops below 9 g/dL in a full-term baby, or your baby seems excessively tired, pale, or is feeding poorly, additional causes of anemia should be investigated. Iron stores from birth begin to be depleted around 4-6 months, which is why iron supplementation or iron-rich foods become important.
4-12 months
By 4-6 months, hemoglobin levels should be recovering and stabilizing. If anemia persists or worsens beyond this point, it is no longer physiologic and warrants investigation. The most common cause of anemia after 4-6 months is iron deficiency, especially in breastfed infants who are not receiving iron supplementation or iron-fortified foods. The AAP recommends iron supplementation for exclusively breastfed infants starting at 4 months and introduction of iron-rich complementary foods at 6 months. Your pediatrician will screen for anemia around 9-12 months of age.
What to Tell Your Pediatrician
- Describe when you first noticed physiologic anemia of infancy - normal hemoglobin drop 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 seems more tired, pale, or is feeding less enthusiastically than usual around 6-8 weeks of age.
- Mention if your premature baby has hemoglobin levels dropping below 8-9 g/dL and seems lethargic or is not gaining weight well.
- 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 mild anemia (hemoglobin 9.5-11 g/dL) around 6-8 weeks of age but is feeding well, active, and gaining weight
- A slight pallor noticed around 2 months of age that does not worsen and your baby is otherwise thriving
- Your premature baby has a slightly lower hemoglobin that your pediatrician is monitoring without immediate concern
- Blood work shows a low hemoglobin at the expected nadir age with an appropriate reticulocyte count beginning to rise
- Your baby seems more tired, pale, or is feeding less enthusiastically than usual around 6-8 weeks of age
- Your premature baby has hemoglobin levels dropping below 8-9 g/dL and seems lethargic or is not gaining weight well
- Anemia that was expected to improve by 3-4 months seems to be persisting or worsening
- Your baby at any age is very pale, breathing rapidly, has a fast heartbeat, is refusing feeds, or is lethargic, as this could indicate severe anemia requiring urgent evaluation and possible transfusion
- Your premature baby develops apnea (pauses in breathing), bradycardia (slow heart rate), or significant feeding difficulties along with worsening anemia
What You Can Do at Home
- Keep track of when you notice physiologic anemia of infancy - normal hemoglobin drop — noting the time of day, duration, and any triggers can help your pediatrician.
- Remember that your baby has mild anemia (hemoglobin 9.5-11 g/dL) around 6-8 weeks of age but is feeding well, active, and gaining weight — this is generally within the range of normal.
- At 0-2 weeks, 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 at any age is very pale, breathing rapidly, has a fast heartbeat, is refusing feeds, or is lethargic, as this could indicate severe anemia requiring urgent evaluation and possible transfusion.
Related Conditions
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.
Iron Deficiency Anemia in Babies
Iron deficiency is the most common nutritional deficiency in young children. Babies are born with iron stores that last about 4-6 months, after which they need dietary iron from breast milk (with supplementation), formula, or iron-rich foods. Untreated iron deficiency can affect brain development and cognitive function, so early detection and treatment are important.
Thalassemia in My Baby - Trait vs Disease
Thalassemia is a group of inherited blood disorders where the body makes abnormal or insufficient hemoglobin, leading to anemia. There are two main types: alpha thalassemia and beta thalassemia. Thalassemia trait (minor) causes mild or no anemia and usually requires no treatment. Thalassemia disease (major or intermedia) causes more significant anemia that may require regular blood transfusions. Most cases are identified through newborn screening. Families with Mediterranean, Middle Eastern, African, or Southeast Asian heritage are at higher risk.
Hereditary Spherocytosis in My Baby
Hereditary spherocytosis (HS) is the most common inherited hemolytic anemia in people of northern European descent. Red blood cells are sphere-shaped instead of disc-shaped, causing them to be trapped and destroyed in the spleen. This leads to anemia, jaundice (yellowing of skin and eyes), and an enlarged spleen. Severity ranges from mild (compensated) to severe. In newborns, it often presents as prolonged or severe jaundice. Most children with HS lead normal lives with monitoring, and some require splenectomy later in childhood.
Related Resources
Frequently asked questions
Is physiologic anemia of infancy - normal hemoglobin drop normal?
When should I call the doctor about physiologic anemia of infancy - normal hemoglobin drop?
When is physiologic anemia of infancy - normal hemoglobin drop normal?
What causes physiologic anemia of infancy - normal hemoglobin drop?
What should I mention to my pediatrician about physiologic anemia of infancy - normal hemoglobin drop?
Is physiologic anemia of infancy - normal hemoglobin drop normal at 0-2 weeks?
Is physiologic anemia of infancy - normal hemoglobin drop normal at 2-8 weeks?
Should I go to the ER for physiologic anemia of infancy - normal hemoglobin drop?
Does physiologic anemia of infancy - normal hemoglobin drop go away on its own?
References
- [1]Baker RD, Greer FR, Committee on Nutrition. Diagnosis and Prevention of Iron Deficiency and Iron-Deficiency Anemia in Infants and Young Children (0-3 Years of Age). Pediatrics. 2010;126(5):1040-1050. AAP
- [2]Ohls RK. Evaluation and Treatment of Anemia in the Neonate. In: Fetal and Neonatal Physiology. 5th Edition. Elsevier. 2017. AAP
- [3]MedlinePlus. Anemia in the Newborn. National Library of Medicine. NIH
Doctor Visit Checklist
Bring this checklist to your next pediatrician visit to discuss Physiologic Anemia of Infancy - Normal Hemoglobin Drop.
Things to mention
- Describe when you first noticed physiologic anemia of infancy - normal hemoglobin drop 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 seems more tired, pale, or is feeding less enthusiastically than usual around 6-8 weeks of age.
- Mention if your premature baby has hemoglobin levels dropping below 8-9 g/dL and seems lethargic or is not gaining weight well.
- 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 seems more tired, pale, or is feeding less enthusiastically than usual around 6-8 weeks of age
- Your premature baby has hemoglobin levels dropping below 8-9 g/dL and seems lethargic or is not gaining weight well
- Anemia that was expected to improve by 3-4 months seems to be persisting or worsening
Urgent signs to report immediately
- Your baby at any age is very pale, breathing rapidly, has a fast heartbeat, is refusing feeds, or is lethargic, as this could indicate severe anemia requiring urgent evaluation and possible transfusion
- Your premature baby develops apnea (pauses in breathing), bradycardia (slow heart rate), or significant feeding difficulties along with worsening anemia
My notes
From ismybabyalright.com — free, evidence-based baby health guides
All content follows our editorial policy and is reviewed against published clinical guidelines.
2,705 evidence-based guides6 authoritative medical sources5 medical advisory board members
Related Resources
Bottom line
Most cases of physiologic anemia of infancy - normal hemoglobin drop are normal. Talk to your pediatrician if your baby at any age is very pale, breathing rapidly, has a fast heartbeat, is refusing feeds, or is lethargic, as this could indicate severe anemia requiring urgent evaluation and possible transfusion.
Trust your instincts. If something feels wrong, reach out to your pediatrician. Worrying about your baby means you care — that is a good thing.
Was this page helpful?
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.
Iron Deficiency Anemia in Babies
Iron deficiency is the most common nutritional deficiency in young children. Babies are born with iron stores that last about 4-6 months, after which they need dietary iron from breast milk (with supplementation), formula, or iron-rich foods. Untreated iron deficiency can affect brain development and cognitive function, so early detection and treatment are important.
Thalassemia in My Baby - Trait vs Disease
Thalassemia is a group of inherited blood disorders where the body makes abnormal or insufficient hemoglobin, leading to anemia. There are two main types: alpha thalassemia and beta thalassemia. Thalassemia trait (minor) causes mild or no anemia and usually requires no treatment. Thalassemia disease (major or intermedia) causes more significant anemia that may require regular blood transfusions. Most cases are identified through newborn screening. Families with Mediterranean, Middle Eastern, African, or Southeast Asian heritage are at higher risk.
Hereditary Spherocytosis in My Baby
Hereditary spherocytosis (HS) is the most common inherited hemolytic anemia in people of northern European descent. Red blood cells are sphere-shaped instead of disc-shaped, causing them to be trapped and destroyed in the spleen. This leads to anemia, jaundice (yellowing of skin and eyes), and an enlarged spleen. Severity ranges from mild (compensated) to severe. In newborns, it often presents as prolonged or severe jaundice. Most children with HS lead normal lives with monitoring, and some require splenectomy later in childhood.
Diamond-Blackfan Anemia in My Baby
Diamond-Blackfan anemia (DBA) is a rare inherited bone marrow failure syndrome where the bone marrow does not produce enough red blood cells. It typically presents in the first year of life, most commonly by 3 months of age, with severe anemia (pallor, poor feeding, rapid breathing). About 50% of affected children also have physical anomalies such as abnormal thumbs, short stature, or craniofacial differences. Most children respond to corticosteroid treatment, while others require regular blood transfusions or bone marrow transplant.
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.