Could breast milk prevent blindness in premature infants?

Breast milk is already known to have many benefits for infants, but a new study has found it may also be beneficial in preventing retinopathy of prematurity (ROP)-one of the leading causes of blindness in children.

Retinopathy of prematurity occurs when blood vessels grow abnormally in the retina. These vessels can leak, causing scarring on the retina and possible detachment of the retina and even blindness in some cases. There are 5 stages of ROP severity, and most children fall into stages I or II, but roughly 3% of the 16,000 to 18,000 babies born with ROP in the United States each year develop blindness. In mild to moderate cases (stages I and II), children with ROP improve with no treatment, but more severe cases are treated with laser therapy or cryotherapy to reverse the abnormal blood vessel growth.

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Risk factors for ROP include anemia, blood transfusions, respiratory distress and treatment with high-concentration oxygen therapy, and poor overall health, but it primarily affects premature infants born weighing less than 1250 grams or before 31 weeks gestation. About half the babies born below 1250 grams or before 31 weeks gestation have some stage of ROP, according to the National Eye Institute.

Advances in the management of preterm neonates has resulted in improved survival rates for the smallest and sickest neonates, but these advances come at a price, and these infants often face life-long chronic illness.

Recent studies have shown an increase in the prevalence of ROP, with a 96% incidence in babies born at 22 weeks gestation and 32% in babies born at 28 weeks gestation in the United States, according to the report.

Retinopathy of prematurity has become the leading cause of childhood blindness and results in blindness for about 50,000 children globally, according to the study, and researchers sought to examine whether human breast milk would be effective in preventing ROP, as it has been shown to prevent other preterm conditions such as necrotizing enterocolitis and late-onset sepsis.

The observational study examined 5 previous studies involving more than 2200 preterm neonates born with an average gestational age of 26 to 30.2 weeks, and a birth weight of 775 grams to 1376 grams. By comparing neonates fed exclusively breast milk, some breast milk and some formula, and exclusively formula, researchers found that the overall incidence of ROP was lower in babies fed some breast milk. Exclusive breastfeeding showed even more significant results in preventing ROP.

According to the study, published in Pediatrics, the risk of developing any stage of ROP dropped by 75% in infants who were fed breast milk exclusively, and the likelihood of developing severe ROP dropped by 90%.

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Researchers believe the preventive effect of breast milk may be attributed to its antioxidants, immune-protective properties, and immunomodulatory substances including secretory immunoglobulin A, lactoferrin, lysozyme, cytokines, oligosaccharides, antioxidant enzymes, and cellular components, according to the report.

“These factors are thought to influence immune defenses of the infant, which may explain the lower risk of necrotizing enterocolitis and sepsis among infants fed human milk,” the study authors note.

Although this study did not review the effects of donor milk on the prevention of ROP, researchers cite a previous study that revealed no benefit of donor breast milk versus formula.

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“This contrast may be possibly related to loss of the protective factors in breast milk during processing and storage,” according to the study.

Faruk H. Örge, MD, director of the Center for Pediatric Ophthalmology and Adult Strabismus at Rainbow Babies and Children’s Hospital and University Hospitals Eye Institute in Cleveland, Ohio, says the benefits of breast milk are plentiful, and he, too, is studying the effects of breast milk on ROP. The multicenter national study is specifically looking at inositol, a non-glucose carbohydrate found in high concentrations in human breast milk.

According to a study published in the Journal of Nutrition, inositol is used as a supplement in infant formulas, and is believed to play a specific role in fetal and neonatal nutrition and development.

“Inositol plays a role in many important biological functions, including the regulation of cell osmolality, phosphoinositide-mediated processes of cell signaling, formation of the neural system, pulmonary surfactant phospholipid production, and host defense,” according to the study. “Several studies have proposed an important nutritional role for inositol in early human development. As early as the first trimester of pregnancy, inositol is concentrated in the intervillus, coelomic, and amniotic fluids compared with maternal serum … At term, inositol concentrations are highest in the umbilical artery compared with the umbilical vein and maternal serum. An uptake of inositol into the placenta from the fetal circulation indicates that there is high fetal inositol production to meet fetal requirements.”

Örge says the phase-3 clinical trial has already demonstrated that inositol reduced ROP in the first 2 phases, and researchers are now working to determine if there is a specific route that inositol should be given to achieve maximum therapeutic benefits. Participants in the study receive an 80 mg myo-inositol 5% injection per kilogram per day in divided doses every 12 hours, beginning within 12 to 72 hours of birth.

The clinical trial is also observing the efficacy of inositol on a number of other conditions that affect preterm infants including bronchopulmonary dysplasia, intraventricular hemorrhage, cerebral palsy, and more.

“As a clinician and ROP expert, I would highly recommend all children be fed breast milk whenever applicable over any other substitute,” Örge says. “Although we are constantly learning more regarding the benefits of breast milk, millions of years of evolution, an optimum source of nutrition, cheaply and organically produced by the mothers, in my opinion, proves to be the best source, especially for the most vulnerable population-the premature babies.”