NEC Link to Baby Formula

Premature birth is a stressful experience for parents and infants. Visions of cradling your newborn baby in your arms in the comfort of your home are replaced with the sight of your child attached to an array of medical equipment inside an incubator, where you may not have the option to hold or even touch your beloved child. This stress is compounded when complications develop. 

Necrotizing enterocolitis, or NEC, is a devastating condition that affects one in 1,000 premature infants. It can come on suddenly, and it can quickly result in death or lifelong complications. Most parents never hear of this condition until it affects their own child.

What is NEC?

Necrotizing enterocolitis is a gastrointestinal disease that causes intestinal inflammation and infection that ultimately leads to the destruction of the intestines. 

  • “Necrotizing” refers to tissue death.
  • “Enterocolitis” refers to inflammation of intestinal tissues.

The bacteria causing the inflammation leads to the death of the intestinal tissues. The tissue damage leads to perforations, or holes, in the intestinal walls, through which the bacteria,  undigested food particles and fecal material can escape and enter the bloodstream. Meanwhile, the surviving tissue becomes swollen and inflamed, making it unable to digest and process food.

Risk Factors

No one knows what causes NEC, but some theories attribute it to immature lung development resulting in reduced oxygenation of the blood. This can deprive the intestines of needed oxygen and damage the intestinal wall. 

The most consistent risk factors for developing NEC are premature birth and baby formula feeding. Other risk factors include the following:

  • Being in a nursery where other infants are affected (outbreaks)
  • Blood transfusions
  • Complicated births
  • Low oxygen levels during birth
  • Intestinal infections
  • Receipt of H2 blockers for reflux
  • Extremely low birth weight

Only one in 10,000 full-term infants gets NEC. Full-term infants who get NEC usually have the following comorbidities:

  • Congenital heart disease
  • Vascular bypass surgery
  • Low birth weight

How does baby formula contribute to the risk?

Formula-fed infants are six to ten times more likely than infants fed their own mother’s milk to develop NEC, and twice as likely as infants fed donor milk. This demonstrates that breast milk may have protective factors against NEC or that formula may have aggravating factors.

While the exact mechanisms are not understood, researchers have found some possible explanations for the connection between NEC and baby formula.

  • Breast milk is easier to digest and provides the baby with the mother’s antibodies, which help the baby resist infections.
  • One study found that the free fatty acids (FFAs) in baby formula caused death to intestinal cells, while the FFAs in human milk did not.
  • A link has been established to oligosaccharides in breast milk that are capable of stimulating the growth of healthy bacterial flora.
  • Current manufacturing processes do not allow for the production of sterilized infant formula, and bacterial contamination has been documented, including contamination by the bacterium Cronobacter sakazakii, which has been identified in the cultures of some infected infants.

What are the symptoms of NEC?

NEC usually develops suddenly when the baby is two to six weeks old and previously appeared healthy. Symptoms of NEC can vary from baby to baby and may mimic other digestive issues. The most common symptoms are as follows:


A belly that is swollen, red or tender


Difficulty with feedings




Diarrhea with dark or bloody stools




Low body temperature


Green vomit


Breathing difficulties


Reduced heart rate


Low blood pressure

Are there any early warning signs?

Most cases are noticed when gastrointestinal symptoms develop. However, in one study of 297 infants, researchers found that cardiorespiratory symptoms preceded gastrointestinal symptoms. 

Cardiorespiratory symptoms refer to changes in breathing, blood pressure and heart rate. This study suggests that any changes in the cardiorespiratory system in preemies should be investigated as potential early symptoms of NEC.

How is NEC diagnosed?

The following tests are used to confirm the presence of NEC:

  • Blood tests are utilized to check for bacteria, sepsis, low platelet counts and low white blood cell counts.
  • Fecal tests are performed to check for blood in the stool.
  • X-rays are taken to look for signs of NEC in the intestines and abdominal areas, such as air bubbles.

Disease Course

As the bacteria ravages the baby’s intestines, oxygenation is lost until complete tissue death ensues, at which time the intestines may turn black. Food can no longer be moved or digested through this portion of the intestines.

The damaged walls can perforate, allowing stool and bacteria to escape into the abdominal cavity and the bloodstream. This can cause sepsis, a toxic response to severe infection which causes tissue damage, organ failure and death. As the condition progresses, the child may experience shock, respiratory failure and ultimately death.

Stages of NEC

Necrotizing enterocolitis is classified by stages, which are a measure of the severity of the illness. Identifying NEC while it is still in stage I improves treatment outcomes. Unfortunately, it is often not diagnosed until it reaches the later stages. 

Each stage has two subclassifications, A and B.

Stage I

Stage IA NEC is when the disease is still suspected based on the following early indications:

  • Gastric retention
  • Abdominal distention
  • Emesis
  • Blood in the stool
  • X-rays show normal or mildly dilated intestines

If the stool contains a large quantity of blood, the stage is upgraded to IB.

Stage II

NEC is categorized as Stage II when the diagnosis is confirmed. Stage IIA is characterized by mild illness that presents with the same symptoms as Stage IA, with the addition of the following:

  • Absent bowel sounds with or without abdominal tenderness (bowel sounds can be detected with a stethoscope)
  • X-rays that show the following:
    • Lack of normal muscle contractions in the intestines
    • Intestinal dilation
    • Pneumatosis intestinalis (the presence of free air or gas in the intestinal wall)

Stage IIB presents as moderate illness with the same symptoms as IIA and the following:

  • Metabolic acidosis
  • Reduced platelets
  • Definite abdominal tenderness
  • Bacterial infection of the abdomen or a mass in the lower quadrant of the abdomen
  • X-rays that show a fluid buildup within the intestines

Stage III

Stage III NEC presents as an advanced stage of NEC with severe illness. Stage IIIA presents with all the symptoms of IIB plus the following:

  • Low blood pressure
  • Reduced heart rate
  • Severe apnea (interruptions in breathing)
  • Combined respiratory and metabolic acidosis
  • Overactive clotting factors
  • Lack of neutrophils, a type of white blood cell that fights infections
  • Abdominal distention

In stage IIIB, the most advanced stage, the bowel is perforated and X-rays show air in the peritoneal cavity, the space occupied by the stomach, liver and intestines.

What is the treatment for NEC?

Treatment for necrotizing enterocolitis is dependent upon the stage of the disease. Cases that are identified early can be treated without surgery and resolved with a decreased likelihood of complications. 

Medical treatment includes the following:

  1. Discontinuance of all feedings. An orogastric tube is inserted to empty the stomach and intestines of air, fluid and any other material
  2. The administration of intravenous fluids and antibiotics
  3. Frequent monitoring through X-rays and examinations

Some infants respond to treatment and can resume feedings within five to seven days after all signs of infection have disappeared and bowel function has returned. 

Infants who do not respond to medical treatment may require surgery to remove the portions of the intestines that are necrotic (dead) or on the verge of rupturing. The doctor attempts to preserve as much of the intestine as possible.

The doctor may need to perform a colostomy, a procedure during which the doctor creates an opening in the abdomen called a stoma. The doctor then brings the intestine out of the abdomen through the stoma to prevent the continued spillage of fecal matter inside the abdominal cavity. 

Bowel movements subsequently occur through the stoma instead of the anus.

After the infant recovers, this operation can be reversed, and bowel movements will resume through the anus. The reversal generally occurs after about six to eight weeks but could take longer depending on the case.

What is the prognosis?

As many as 40 percent of infants with NEC die from it. Early detection during stage I with aggressive medical treatment is the most important factor in the outcome. Many patients recover and live normal lives, but some patients, especially those with severe cases that require surgery, develop long-term complications.

Long-Term Effects

Lasting complications are not uncommon in the aftermath of NEC.

Gastrointestinal Complications

The following conditions can develop secondary to necrotizing enterocolitis:

  • Intestinal strictures. This is a narrowing of the intestines, a condition that can prevent food from passing through. This condition often develops months after recovery and may require surgery.
  • Short bowel/short gut syndrome. This condition occurs when portions of the intestine had to be removed, resulting in a smaller amount of intestinal surface area to absorb nutrients. Children with this condition require lifelong care and may need tube feedings.

Neurodevelopmental Impairment

Neurodevelopmental delays and impairments have been observed at higher rates in children who had NEC. The exact etiology is not well-understood. It may be due to the brain’s vulnerability during this early stage of life, nutritional deficiencies and other factors present throughout the course of the disease.

An 11-year study found that 61 percent of children who had recovered from NEC experienced neurological impairments, with a 67 percent incidence among those who required surgery. These impairments were observed as follows:

  • Cognitive impairment – 56 percent
  • Motor impairment – 33 percent
  • Special education needs – 56 percent
  • Learning disabilities – 50 percent
  • Speaking difficulties – 33 percent
  • Cerebral palsy – 22 percent

Can NEC be prevented?

NEC is not 100 percent preventable because the causes of this devastating condition are still poorly understood. Researchers are working toward identifying the cause. 

Recent findings include the following early indications that NEC could develop:

  • Decreased development of tiny blood vessels in the intestines and a subsequent reduction in the growth hormone IGF-1 (insulin-like growth factor) 
  • Marked change in the naturally-occurring viral organisms in the infant’s gastrointestinal tract immediately preceding the development of NEC

Experimental research has discovered the following promising protocols that could both treat and prevent NEC:

  • Probiotics (“good” bacteria) to oppose pathogenic bacteria
  • Blocking the production of nitric oxide, a substance known to aggravate NEC

This groundbreaking research offers hope that this terrible disease will one day be eradicated. 

Until the causes are better understood, the following measures can help decrease your baby’s chances of developing NEC:

  • Premature birth is not always preventable, but quality prenatal care beginning in early pregnancy can reduce the risk.
  • If possible, only feed breast milk to newborn infants, especially premature infants. If your own breast milk is not an option, donor milk may be available.
  • If formula feeding is the only option, don’t panic. The risk is still low, but be aware of the early symptoms of NEC and be alert to the early warning signs.

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