A 4-month-old baby developed life-threatening brain bleeding despite receiving a vitamin K injection at birth, likely because an infection interfered with his body’s ability to use vitamin K. According to Gram Research analysis of this case report, the baby’s blood couldn’t clot (INR greater than 4, normal is less than 1.1) after an antibiotic injection, but recovered quickly after emergency vitamin K treatment. The case shows doctors must stay alert for unexpected bleeding in young infants with infections and treat vitamin K deficiency immediately.
A 4-month-old baby received a vitamin K injection at birth to prevent bleeding problems, but still developed severe bleeding in the brain that caused seizures. According to Gram Research analysis, this case report from a resource-limited setting shows that vitamin K deficiency bleeding can still happen even after the standard newborn vitamin K shot, especially when babies have infections or other risk factors. The baby recovered after emergency treatment with vitamin K and supportive care, but the case highlights why doctors need to stay alert for unexpected bleeding in young infants and act quickly with treatment.
Key Statistics
A 2026 case report documented a 4-month-old infant who developed severe coagulopathy with INR greater than 4 and brain bleeding despite receiving standard neonatal vitamin K prophylaxis, likely triggered by concurrent infection.
In this case, the infant’s blood clotting parameters (PT and aPTT both greater than 120 seconds, normal range 11-35 seconds) normalized rapidly after parenteral vitamin K administration, though seizures and subdural hematoma had already developed.
Late-onset vitamin K deficiency bleeding occurred in this 4-month-old infant who was predominantly formula-fed with occasional breastfeeding, demonstrating that mixed feeding patterns do not eliminate risk when other factors like infection are present.
The Quick Take
- What they studied: A single case of a 4-month-old baby who developed life-threatening brain bleeding despite receiving a vitamin K shot at birth
- Who participated: One male infant, 4 months old, born by cesarean section with a birth weight of 3200 grams, who received standard vitamin K prophylaxis at birth
- Key finding: The baby developed severe bleeding problems and brain bleeding (subdural hematoma) at 4 months old, even though he had received the recommended vitamin K injection at birth, likely due to an infection that interfered with vitamin K absorption
- What it means for you: Parents should know that while vitamin K shots at birth are highly protective, babies with infections or feeding problems may still need careful monitoring. Doctors should suspect vitamin K deficiency bleeding if a baby develops unexpected bleeding, especially after injections or minor procedures, and should treat it immediately with vitamin K and blood transfusions if needed
The Research Details
This is a case report, which means doctors documented the medical story of one specific patient to teach other healthcare providers about an unusual or important situation. The baby came to the hospital with fever, cough, and poor appetite at 4 months old. Doctors initially thought he had a blood infection (sepsis) and gave him an antibiotic injection. Within hours, the injection site started bleeding heavily, and blood tests showed his blood couldn’t clot properly. Doctors gave him emergency vitamin K treatment and discovered he had bleeding inside his brain.
Case reports are the simplest type of medical research—they’re like detailed medical stories rather than experiments comparing large groups of people. They’re useful for alerting doctors to rare problems or unexpected complications, but they can’t prove that something causes a disease because there’s no comparison group. This case is important because it shows that vitamin K deficiency bleeding can still occur in babies who received the standard protective shot at birth.
The doctors carefully documented what happened, what tests showed, and how the baby responded to treatment. They noted that resource limitations prevented them from completely ruling out other causes of bleeding, which is an important limitation to understand.
Case reports like this one serve as early warning systems for doctors. By sharing this story, the doctors alert other healthcare providers around the world to watch for vitamin K deficiency bleeding in infants, even those who received the standard preventive shot. This is especially important in resource-limited settings where infections are more common and babies may have less access to follow-up care. The case shows that doctors need to think about vitamin K deficiency when babies develop unexpected bleeding, particularly if they have infections or feeding problems.
As a single case report, this study cannot prove that vitamin K deficiency caused the bleeding or determine how often this problem occurs. However, the detailed documentation of the baby’s symptoms, test results, and response to treatment makes it a credible observation. The doctors were honest about limitations—they couldn’t completely rule out other causes of bleeding due to limited resources. The fact that the baby’s blood clotting improved after vitamin K treatment and that his symptoms matched known patterns of vitamin K deficiency bleeding makes the diagnosis likely, though not certain. Readers should understand this is one doctor’s detailed observation, not proof that this will happen to other babies.
What the Results Show
The 4-month-old baby arrived at the hospital with fever, cough, and loss of appetite. Blood tests showed he had low hemoglobin (a protein that carries oxygen) at 9 grams per deciliter and high white blood cells, suggesting infection. Doctors gave him an antibiotic injection to treat suspected blood infection. Within a short time, the injection site developed a large, expanding bruise with active bleeding—a sign that something was very wrong with the baby’s ability to clot blood.
Urgent blood clotting tests revealed severe problems: his INR (a measure of clotting ability) was greater than 4 (normal is less than 1.1), his PT (prothrombin time) was greater than 120 seconds (normal is 11-13.5 seconds), and his aPTT (another clotting test) was also greater than 120 seconds (normal is 25-35 seconds). His hemoglobin dropped dangerously to 6.3 grams per deciliter. These results showed his blood couldn’t clot at all.
Doctors immediately gave him vitamin K by injection. His blood clotting improved quickly after this treatment. However, the baby then developed seizures and his consciousness deteriorated. Brain imaging showed he had bleeding inside his brain (subdural hematoma) and damage from lack of oxygen. Despite these serious complications, the baby was treated in the intensive care unit with seizure medications, blood transfusions, antibiotics, and supportive care. His seizures stopped, his brain function returned to normal, and he was discharged after 10 days without obvious lasting brain damage.
The baby’s response to vitamin K treatment was dramatic and rapid, with blood clotting parameters returning to normal within hours. This quick improvement after vitamin K strongly suggested vitamin K deficiency was the underlying problem. The baby had received the standard 1-milligram vitamin K injection at birth, which is highly effective at preventing this problem in most infants. The fact that he still developed vitamin K deficiency bleeding suggests that something interfered with his vitamin K absorption or storage—likely the infection he had at 4 months old. The baby’s feeding pattern (mostly formula with occasional breastfeeding) was also noted, as exclusive breastfeeding without vitamin K supplementation is a known risk factor for late-onset vitamin K deficiency bleeding.
Vitamin K deficiency bleeding in infants is a well-known but preventable condition. The standard practice of giving all newborns a vitamin K injection has dramatically reduced cases of this life-threatening bleeding. However, medical literature has documented that late-onset vitamin K deficiency bleeding (occurring between 2 weeks and 6 months of age) can still happen, especially in babies with infections, malabsorption problems, or exclusive breastfeeding without vitamin K supplementation. This case fits the known pattern of late-onset vitamin K deficiency bleeding presenting with brain bleeding, which is the most common and most dangerous form. The case is notable because it occurred despite the standard preventive vitamin K shot, highlighting that additional risk factors (in this case, infection) can overcome the protection provided by the birth dose.
This is a single case report, so it cannot determine how often this problem occurs or prove cause-and-effect relationships. The doctors acknowledged that resource limitations prevented them from completely ruling out other causes of bleeding problems, such as inherited clotting disorders or other infections. The baby’s complete medical history before arriving at the hospital is not fully documented. We don’t know if the vitamin K injection at birth was actually given or if it was given correctly, since this information came from the parents’ report. The case cannot tell us whether this baby’s outcome would have been different if he had received vitamin K supplementation earlier or if he had been exclusively formula-fed instead of breastfed. Finally, because this is one baby’s story, we cannot apply these findings to all infants without more research.
The Bottom Line
Healthcare providers should maintain high suspicion for vitamin K deficiency bleeding in infants aged 2 weeks to 6 months who develop unexpected bleeding, especially after injections or minor procedures, and particularly if the baby has an infection (moderate to high confidence based on established medical knowledge and this case). Prompt treatment with vitamin K and blood transfusions can be life-saving. Parents should ensure their newborns receive the standard vitamin K injection at birth and should report any unusual bleeding to their doctor immediately. In resource-limited settings, doctors should be especially alert because infections are more common and may trigger vitamin K deficiency bleeding even in vaccinated infants (moderate confidence).
Pediatricians, emergency room doctors, and nurses in all settings should be aware of this risk, especially those working in resource-limited areas where infections are more common. Parents of infants aged 2 weeks to 6 months should know the warning signs of bleeding problems. Babies with infections, feeding difficulties, or exclusive breastfeeding without vitamin K supplementation are at higher risk. This case is less relevant to parents of babies in developed countries with strong healthcare systems and routine vitamin K prophylaxis, but the warning signs apply everywhere.
Vitamin K deficiency bleeding can develop suddenly and progress rapidly, as shown in this case where the baby went from appearing to have a simple infection to having life-threatening brain bleeding within hours. Treatment with vitamin K works quickly to restore blood clotting ability (within hours), but brain damage from bleeding may take weeks or months to fully resolve. Long-term neurological follow-up is important because some babies may have delayed developmental problems even if they appear normal at discharge.
Frequently Asked Questions
Can a baby get vitamin K deficiency bleeding even after the newborn vitamin K shot?
Yes, late-onset vitamin K deficiency bleeding can occur between 2 weeks and 6 months of age despite the standard birth dose, especially if the baby has an infection or feeding problems. This 2026 case report documents a 4-month-old who developed brain bleeding despite receiving vitamin K at birth, likely because infection interfered with vitamin K absorption.
What are warning signs of vitamin K deficiency bleeding in babies?
Watch for unexpected bruising, bleeding from injection sites, blood in vomit or stool, seizures, or unusual fussiness and poor feeding. This case showed an expanding bruise at an injection site followed by seizures and brain bleeding. Any unexpected bleeding in an infant requires immediate medical evaluation.
How quickly does vitamin K treatment work for bleeding problems in babies?
Vitamin K treatment works rapidly to restore blood clotting ability, often within hours. In this case, the infant’s severely abnormal clotting tests (INR greater than 4) normalized after vitamin K injection, though brain damage from bleeding had already occurred, emphasizing the importance of early recognition and treatment.
Are babies who are breastfed at higher risk for vitamin K deficiency bleeding?
Exclusively breastfed babies without vitamin K supplementation have higher risk for late-onset vitamin K deficiency bleeding. This case involved mixed feeding (mostly formula with occasional breastfeeding), showing that even mixed feeding doesn’t eliminate risk when infections are present.
What should I do if my baby develops unexpected bleeding or bruising?
Seek immediate medical attention. Tell your doctor about any fever, infection, or recent injections. Vitamin K deficiency bleeding can progress rapidly and cause brain bleeding, but prompt treatment with vitamin K and blood transfusions can be life-saving, as demonstrated in this case.
Want to Apply This Research?
- Parents of infants should track any unusual bleeding or bruising, including the size and location of bruises, bleeding from injection sites, or blood in vomit or stool. Note the timing relative to infections, fever, or medical procedures. This information helps doctors quickly identify vitamin K deficiency bleeding.
- Ensure your newborn receives the standard vitamin K injection at birth and document it in your baby’s medical records. If your baby is exclusively breastfed, discuss vitamin K supplementation with your pediatrician. If your baby develops fever or infection, watch carefully for any signs of unusual bleeding and report them immediately to your doctor.
- During the first 6 months of life, especially if your baby has an infection or feeding problems, monitor for warning signs: unexpected bruising, bleeding from injection sites, blood in vomit or stool, or unusual fussiness and poor feeding. Keep a record of any infections and their timing. Maintain regular pediatric check-ups and discuss any concerns about bleeding or bruising immediately.
This case report documents one infant’s experience and cannot be applied to all babies. Vitamin K deficiency bleeding is rare in infants who receive standard vitamin K prophylaxis at birth. This information is educational and not a substitute for professional medical advice. If your infant shows signs of unusual bleeding, bruising, or has seizures, seek immediate emergency medical care. Always consult with your pediatrician about your baby’s vitamin K status and any concerns about bleeding or bruising. The findings in this case are limited by resource constraints that prevented complete exclusion of alternative causes of bleeding.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.