Got Milk? Cow’s Milk Infant Formula And The Risk Of Developing Necrotizing Enterocolitis In Premature Infants

By Sara Papantonio

Premature infants who are fed Similac or Enfamil formula while being treated in the neonatal intensive care units are developing necrotizing enterocolitis (NEC) at an alarming rate. For years, cow’s milk-based formulas, like Similac and Enfamil, have been associated with a higher risk of NEC in premature babies when compared to breast milk. But, until recently, little had been done to hold the manufacturers of these products responsible for their role in harming thousands of premature infants across this country.

Breast Milk vs. Cow’s Milk

Human breast milk is nature’s purest form of nutrition. It is the sustenance that allows our most vulnerable population — newborn babies — the ability to grow and develop into healthy adults. For some mothers, human breast milk is not a viable option for nutrition and others where the mother prefers not to breastfeed. In those circumstances, mothers frequently rely on manufactured formulas to replace breast milk. Manufactured formulas are made with cow’s milk that is altered to mimic breast milk. Mothers and fathers turn to the formula in hopes that it will aid the child’s growth and development in the same way as human breast milk. However, for infants born prematurely these manufactured cow’s milk formulas are not promoting growth, but rather causing NEC, an often-fatal disease.

Until the 1960s, premature babies were exclusively fed an all human-milk based diet. If a mother’s milk was not a viable option, donor breast milk would typically be provided to the infant. Around this time, formula companies like Abbott Laboratories and Mead Johnson Nutrition began developing cow’s milk-based formula to serve as an alternative to human milk. By the 1980s, these formula companies were successfully promoting a cow’s milk based formula, as the best alternative or replacement to human milk. These cow’s milk formulas were specially designed to promote growth and provide the same type of nutrients a child would receive from human milk. For fully developed babies, the cow’s milk formulas were often adequate alternatives. However, over time, it has become clear that these cow’s milk formulas place premature babies at a significantly higher risk of developing NEC.

The National Institute of Child Health and Human Development estimates that NEC affects about 9,000 of the 480,000 infants born preterm each year in the United States. NEC results from inflammation of the small intestine or colon that ultimately causes the tissue to necrotize or die. NEC begins with tiny perforations in the infant’s digestive tract, which causes bacteria to leak into the infant’s abdomen or bloodstream. When a child develops NEC, it can lead to organ failure or even death. Those infants that survive NEC are typically faced with long-term injuries such as intestinal failure, short gut syndrome, and/or developmental delays.

Science Favors Human Milk

A growing body of evidence suggests that there is a statistically significant relationship between cow’s milk-based formula and NEC in premature infants.

While the biological mechanism for the development of NEC with the use of cow’s milk-based formula is not fully understood, studies have found that the unbound free fatty acids in cow’s milk likely makes the formula cytotoxic in premature infants. The formula’s cytotoxicity likely results in damage to the intestinal wall of premature infants. Many believe that premature babies do not have a fully developed digestive system that is capable of breaking down the cow’s milk formula, which puts the babies at greater risk of developing NEC. Additionally, premature infants have a weakened immune system, which prevents the infant from fighting infection once that infectious process begins to develop. As a result, once NEC develops it is difficult for a premature infant to fight it off.

Despite the developing literature on the biological mechanism for NEC, decades’ worth of research suggests that preterm babies should not be fed cow’s milk-based formulas. Companies like Abbott and Mead have been on notice of the risk of NEC in preterm babies since at least the early 1990s. For example, in 1990 The Lancet published a study finding that preterm babies who were exclusively fed formula were 6 to 10 times more likely to develop NEC than those infants fed breast milk. Further, the study predicted “exclusive formula feeding could account for an estimated 500 extra cases of necrotizing enterocolitis each year [and] about 100 of these infants would die.” Yet still, over 30 years later, companies like Abbott and Mead continue to advertise cow-milk formulas as being safe and viable alternatives for preterm infants.

The evidence linking cow’s milk formula and NEC in premature infants has only grown stronger in the last decade. In 2010, a clinical study found that “an exclusively human milk diet had significantly lower rates of necrotizing enterocolitis and NEC requiring surgical intervention.” Further, the study predicted that reducing instances of NEC by half would prevent between 1,300 and 1,850 NEC cases per year. Another clinical study conducted in 2014 compared human milk to cow’s milk formula from the perspective of impact on mortality and morbidity. The study ultimately found that human milk diets were associated with lower rates of mortality and morbidity. It is also important to note that the human milk diet, as opposed to a cow’s milk diet, did not compromise growth in study subjects.

The significance of these studies has likely influenced statements from health authorities. In 2011, the Surgeon General stated “for vulnerable premature infants, formula feeding is associated with higher rates of necrotizing enterocolitis.” Similarly in 2012, the American Academy of Pediatrics, echoed the Surgeon General’s warning by stating that “all preterm infants should be fed either their mother’s milk or, if their mother’s milk is unavailable, pasteurized human donor milk.”

Yet still, despite these warnings, Abbott and Mead continue to market the cow’s milk formula as a formula for premature infants. The cow’s milk formulas are peppered with statements such as “for babies born prematurely” and premature baby formula that is “specifically formulated for your preemie’s unique needs.” And most importantly, these products remain devoid of any warning concerning their propensity to cause NEC.

Reasonable Alternatives Exist

Human donor milk and human milk based formulas serve as reasonable alternatives to cow’s milk formula for preterm babies. In 2006, a company named Prolacta began manufacturing a human milk-based formula. Importantly, Prolacta’s human-based products have been found to reduce the NEC in premature infants by up to 77 percent when compared to cow’s milk. Prolacta’s products have also been found to be as effective as human breast milk and cow’s milk formulas. In a study where infants were fed an exclusive human milk-based diet, it was found that human milk-based diets “exceeded standard growth targets and met length and head-circumference growth targets, demonstrating that infants can achieve and mostly exceed targeted growth standards when receiving an exclusive human milk-based diet.”

Status Of The Litigation

Cases are being filed around the country both in state and federal courts. Thus far, many have been moving forward successfully. The plaintiffs’ complaints primarily allege claims against the formula manufacturers for design defect, failure to warn, and negligence. On the state court front, a motion to consolidate nearly 40 cases in Madison County, Illinois has been granted. Federal cases have been filed in the District of Connecticut, Central District of California, and District of Columbia. It is expected that many more infant formula cases will be filed in federal court in the months to come. Given the amount of plaintiffs and the commonality of this injury, this case is likely headed toward a multi-district litigation.


For decades, formula companies like Abbott and Mead have been on notice of the increased risk of NEC in premature infants that is associated with their cow’s milk formulas. Yet, the companies have still failed to change their labels to warn hospitals, doctors and families of this increased risk. Until these companies take measures to ensure their products are safe and protect premature infants from developing NEC, our most vulnerable population of children will remain at unnecessary risk.

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