Feeding Preterm Newborns Breast Milk May Help Prevent ROP

Diedtra Henderson

November 16, 2015

Feeding very preterm newborns human milk may help prevent retinopathy of prematurity (ROP), according to a meta-analysis published online November 16 in Pediatrics.

"The meta-analysis results of our study indicate that the overall incidence of ROP was reduced among infants fed human milk compared with those fed formula, and exclusive or mainly human milk feeding showed significant benefits in preventing severe ROP," write Jianguo Zhou, MD, from the Children's Hospital of Fudan University, Shanghai, China, and colleagues.

Up to 37% of very prematurely born infants (birth weight <1250 g) develop severe ROP, a vasoproliferative disorder of immature retina and a leading cause of blindness in developed countries, according to the authors. To ascertain the potential protective effect of breast milk compared with formula, the authors searched electronic databases for relevant studies and reviewed 312 studies in full.

Five cohort studies conducted from 1992 to 2008 involving 2208 preterm infants met their inclusion criteria. The newborns' average gestational age ranged from 26 to 30.2 weeks, and their birth weight ranged from 775 to 1376 g.

Among infants who were exclusively fed human milk, the risk of developing any-stage ROP was 0.29 (95% confidence interval [CI], 0.12 - 0.72) compared with infants fed any formula. The risk was also significantly lower for infants exclusively fed human milk compared with those exclusively fed formula (odds ratio [OR], 0.25; 95% CI, 0.13 - 0.49). There were nonsignificant trends for infants fed any human milk vs infants fed exclusive formula (OR, 0.54; 95% CI, 0.15 - 1.96) and those fed mainly milk vs mainly formula (OR, 0.51; 95% CI, 0.26 - 1.03), but these differences were not statistically significant.

When the researchers restricted their analysis to the risk for severe ROP, the benefit associated with breast milk appeared larger and reached statistical significance for all comparisons except those fed any milk vs exclusive formula (OR, 0.42; 95% CI, 0.08 - 2.18). Specifically, exclusive human milk vs any formula showed an OR of 0.11 (95% CI, 0.04 - 0.30), mainly human milk vs mainly formula had an OR of 0.16 (95% CI, 0.06 - 0.43), and exclusive human milk vs exclusive formula had an OR of 0.10 (95% CI, 0.04 - 0.29).

Dr Zhou and colleagues theorize that breast milk's protective power may lie in its antioxidant and immune-protective properties. "In vitro chemical analysis of antioxidant content consistently shows that human milk contains vitamin C, vitamin E, and β-carotene and has greater antioxidant properties than formula," the researchers write. "In addition to the antioxidant properties, human milk also contains immunomodulatory substances such as secretory immunoglobulin A, lactoferrin, lysozyme, cytokines, oligosaccharides, antioxidant enzymes, and cellular components."

Because it would be unethical to withhold breast milk from infants, prospective randomized studies are impossible, Dr Zhou and coauthors write. In addition to relying solely on observational studies, another limitation of their meta-analysis is that retrospective data about breast-feeding may underestimate or overestimate the volume of breast milk infants drank.

"After unifying the definitions of feeding and ROP diagnosis and pooling the data, we found that human milk feeding potentially plays a strong role in protecting very preterm newborns from any-stage ROP and severe ROP," the authors conclude.

The authors have disclosed no relevant financial relationships.

Pediatrics. Published online November 16, 2015.

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