Baby Formula and NEC

Necrotizing enterocolitis, commonly known as NEC, is a medical condition that leads to inflammation in the small and large intestines of newborn infants. Any infant may get NEC, but babies born prematurely or who are sick are more likely to get it.

Inflammation caused by NEC can cause several complications such as organ problems, intestinal tissue death, bowel obstruction, nutrient malabsorption, vitamin deficiencies, feeding difficulties and bacteria overgrowth. Bacteria can enter holes in the intestine and lead to deadly infections, such as sepsis.

Treatments for NEC include antibiotics and surgery. Doctors may remove a part of the baby’s bowel and check for holes in the intestinal tract. Babies will stay in the hospital for observation and treatment. Once babies are eating and not losing weight, they may be able to go home.

Babies with severe or worsening NEC may develop generalized swelling or fluid retention and low blood sodium levels. As NEC worsens, babies develop kidney problems and excessive potassium in the blood.

One of the first studies to link baby formula to NEC was a 1990 study that found premature babies fed formula were up to 10 times more likely to develop NEC. Breast milk didn’t show the same risk, and researchers have found that human breast milk may reduce the risk of NEC.

Researchers have hypothesized that antibodies, growth factors and immune cells in breast milk may be protective to a premature baby’s gut and this may prevent NEC. Cow’s milk baby formulas may be more difficult to digest and could cause inflammation that contributes to NEC, but more studies are needed.

Scientists continue to study the effects of formula on a baby developing NEC. Most recently, a clinical trial that began in 2021 and will continue through 2024 is set to gather data on infants fed formula or breast milk to better understand the link.

Premature babies, babies who are sick or born with birth defects are at increased risk of developing NEC. It’s most common in preemies born before 37 weeks, according to the National Organization for Rare Disorders.

Babies born premature and under two pounds have the greatest risk. Formula feeding with cow’s milk baby formula can further increase the risk.

About one in 1,000 premature babies and about one in 10,000 full-term babies may get NEC. Most babies develop NEC while still in the hospital.

Feeding premature babies mother’s milk or human milk from a donor may lower the risk of NEC.

Cow’s milk formulas — such as Enfamil, Similac and other brands — have the greatest chance of causing NEC compared to breast milk. A July 2022 animal study in Frontiers in Pediatrics found that some preterm baby formulas may be more damaging to the gut than others.

“Our findings indicate that not all preterm formulas are the same, and different formulations can have varying effects on intestinal inflammation, apoptosis and microbiome composition,” study authors wrote.

For example, researchers found that Similac Special Care caused more intestinal injury than NeoSure. Similac Special Care is a popular formula for preemies in the neonatal intensive care unit because it’s designed to help them grow and heal. NeoSure is a catch-up growth formula for premature babies who have already gone home from the hospital.

In February 2022, Abbott issued a baby formula recall for Similac, Alimentum and EleCare after some babies died of Cronobacter sakazakii infections. All affected formulas came from Abbott’s Sturgis, Michigan, plant.

Abbott closed the plant to conduct investigations on bacterial contamination. The U.S. Food and Drug Administration has since inspected the plant and found Cronobacter in certain areas around the plant but not in product samples it tested. The recall and plant closure contributed to a national baby formula shortage, but the plant is back open.

In October 2022, Abbott issued another recall for certain lots of its ready-to-feed liquid formulas because some bottle caps might not have been sealed properly. Improperly sealed bottles could cause spoilage, leading to stomach problems in children who consume the formula.

Brands in this recall include Similac Pro-Total Comfort, Similac 360 Total Care, Similac 360 Total Care Sensitive, Similac Special Care 24, Similac Stage 1, Similac NeoSure, Similac water (sterilized) and Pedialyte electrolyte solution.

Parents whose premature babies developed NEC after consuming Enfamil or Similac have filed baby formula lawsuits against manufacturers Abbott Laboratories and Mead Johnson.

Lawsuits claimed that the companies knew or should have known that cow’s milk baby formula could cause NEC in preterm infants. But manufacturers continued to sell the formula and failed to warn parents and doctors.

In August 2022, judges consolidated baby formula lawsuits from across the country in Illinois multidistrict  litigation. As of Dec. 15, 2022, there were 88 cases pending.