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How Human Milk Allows Preemies to Catch Up

A diet of human milk allows the smallest of preemies to catch up on weight gain, new research confirms.

The study, published in the Archives of Disease in Childhood Fetal & Neonatal, followed preemies from their NICU discharge until they were about two years old.  Researchers considered two groups of preemies – those whose birthweight was appropriate for their gestational age, and those whose weight was especially low, even accounting for their prematurity.  Both groups were given an exclusive human milk diet while in the NICU. That is, they received only their mother’s breastmilk or donor milk, along with human-milk based fortifier. The infants did not receive bovine-based formula or fortifier.

The results suggest that an exclusive human milk diet can be a boon for both groups, but especially for the smallest of preemies.  From their first visit with researchers, at 12-15 months, to their second visit at 18-22 months, their body mass index spiked – even more so than their fellow preemies whose weight had been gestational-age appropriate at birth.

Even better, the smallest preemies played catch up without complications like insulin resistance or metabolic disorders. Past research has suggested that premature infants who were born small for their age and then experienced rapid catch-up growth could become obese or insulin resistant later on.  Research had also questioned whether preemies on a human milk diet might be limited in their ability to achieve catch-up growth. This study was the first to measure preemies’ growth over time, gauging catch-up growth as well as metabolic responses.

While the study was small, its findings add to a growing body of research supporting the benefits of an exclusive human milk diet.  The diet has been shown to decrease infants’ risk of a deadly intestinal condition known as NEC (necrotizing enterocolitis).  An exclusive human-milk based diet can also decrease infants’ chances of other complications – infections, a chronic lung disease known as bronchopulmonary dysplasia and the eye disease retinopathy of prematurity.

But while research continues to demonstrate benefits, access to human milk is spotty.  Not all hospitals have donor milk or human milk-based fortifier available, and not all insurance or Medicaid programs cover the cost.  

As the benefits of human milk become increasingly apparent, however, policymakers might be wise to ask themselves just how much access could actually save – in avoidable costs to the health care system, in expense and heartache for the families of preemies, and in the lives and quality of life of vulnerable infants.