The sweet smell of a baby is usually not a cause of concern for parents, especially when there are no obvious signs of illness. However, that was not the case of Megan Popps and Devaughn Debelak, who welcomed their son, Leo, in February 2026. The baby initially appeared healthy and was discharged from hospital after his routine heel-prick screening. Later, Megan noticed that Leo sometimes smelled 'sickeningly sweet', almost like maple syrup or pancakes. Megan said, "While we were still in the hospital, Leo had the heel prick test done and we were discharged home before the results came back."

She added, "We were told we needed to have the test redone as something had come back inconclusive. We went the next day to have it redone. I called up and found out it was Leo's amino acid profile that had come back inconclusive. I looked that up and got the results for MSUD."

After being diagnosed with MSUD, Leo spent three weeks in the hospital, which included treatments that helped remove harmful substances from his blood. Megan said, "MSUD can be controlled with diet. Leo will have to be on a specialised diet for the rest of his life. He will be on a very strict vegan diet, he will have to avoid meat and dairy completely. He will have to count his protein intake for the rest of his life."

What Is Maple Syrup Urine Disease?

Maple Syrup Urine Disease is a rare genetic disorder in which the body cannot properly break down three particular amino acids: leucine, isoleucine and valine. These are known as branched-chain amino acids and are found naturally in protein-rich foods such as meat, dairy products, eggs, beans and other foods. The condition occurs because of problems with a group of enzymes called the branched-chain alpha-ketoacid dehydrogenase complex. Normally, these enzymes help the body process the three amino acids. In people with MSUD, this process does not work properly, causing the amino acids and their related substances to build up in the blood and tissues.

Why Does The Baby Smell Like Maple Syrup?

The unusual smell is one of the most distinctive features of MSUD. The urine, sweat and earwax of affected babies can develop a sweet smell resembling maple syrup, caramel or burnt sugar.

However, not every baby with MSUD will immediately have a noticeable smell. Parents should not rely on this symptom alone. Newborn screening is particularly important because MSUD can become dangerous before obvious symptoms develop.

What Are The Symptoms Of MSUD?

Symptoms can appear within days after birth, particularly when MSUD is not detected and treated. They may include:

  • Poor feeding or difficulty feeding
  • Vomiting
  • Excessive sleepiness or lethargy
  • Irritability
  • Weakness or abnormal muscle tone
  • Abnormal movements
  • A sweet maple syrup-like smell
  • Changes in consciousness
  • Seizures

As toxic substances build up, the brain can become severely affected. Babies may develop swelling in the brain, lose consciousness and eventually fall into a coma. In severe cases, an untreated metabolic crisis can be life-threatening.

What Causes A Metabolic Crisis?

People with MSUD are at risk of episodes called metabolic crises, during which harmful substances rapidly accumulate in the body. These episodes can be triggered by factors such as infections, fever, vomiting, prolonged fasting, dehydration or significant physical stress. Eating more protein than the body can process can also cause amino acid levels to rise. This is why managing MSUD requires careful attention throughout life.

How Is MSUD Treated?

Treatment focuses on preventing the harmful buildup of amino acids while ensuring the child receives enough nutrients for normal growth and development. Babies and children with MSUD usually need a carefully controlled, protein-restricted diet. They may require specialised medical formulas that provide essential nutrients while limiting the branched-chain amino acids that their bodies cannot process properly.

The exact diet is individualised by specialists and dietitians. Foods containing natural protein, including meat and dairy, may need to be restricted, but this should only be done under medical supervision because growing children still need adequate nutrition.

During a metabolic crisis, urgent hospital treatment may be required. This can include intravenous fluids, specialised nutrition and, in severe cases, dialysis to rapidly remove harmful substances from the blood.

Why Is Early Diagnosis Important?

Without treatment, MSUD can cause severe neurological damage, seizures, coma and potentially death. However, early diagnosis and careful lifelong management can significantly improve outcomes.

For parents, an unusual symptom does not necessarily mean a baby has a rare disease. But persistent or unexplained changes, especially alongside poor feeding, vomiting, unusual sleepiness or abnormal movements, should be discussed with a doctor.

Disclaimer: This content including advice provides generic information only. It is in no way a substitute for a qualified medical opinion. Always consult a specialist or your own doctor for more information. NDTV does not claim responsibility for this information.