Preterm Formula Has Benefits Beyond the Hospital Period: Study

Megan Brooks

August 08, 2011

NEW YORK (Reuters Health) August 8, 2011 — Giving preterm formula for at least six months to very low birth weight (VLBW) babies, instead of stopping it when they leave the hospital, might help improve their metabolic profile, a new study suggests.

"We believe that our results lend important support to the concept that feeding practices in the perinatal period have important and long-lasting consequences on health," the study team concludes in the July 25 online issue of The Journal of Pediatrics.

They say their findings also add to evidence that giving nutrient-enriched formulas after discharge leads to early rapid growth with no increase in central adiposity.

Preterm VLBW infants who survive are prone to develop chronic morbidities, including obesity and insulin resistance, Dr. Veronica Mericq of the University of Chile in Santiago and colleagues note in their paper.

The aim of early nutrition is to reduce the incidence of growth restriction while limiting unwanted long-term health consequences that rapid growth may entail.

"Avoiding the putative adverse effect of early rapid growth on body composition in very low birth weight children is an important goal when designing feeding regimens," the researchers point out.

They explored whether prolonged use of nutrient-enriched formulas can improve the trend toward an altered body composition (i.e., more adiposity) and increased fasting insulin levels.

They analyzed 185 preemies with a gestational age of less than 32 weeks or weighing less than 1500 grams. Ninety-five were fed preterm formula for at least six months and 87 were fed preterm formula only during their stay in the neonatal intensive care unit.

All preterm formulas provided more essential lipids (polyunsaturated fatty acids, including docosahexaenoic acid), as well as more total calories, protein, minerals, and micronutrients compared with term formula.

At baseline, the infants in the two groups were well matched in terms of birth weight, birth length, head circumference, gestational age, sex, percentage with a birth weight less than 1 kg, and percentage born small for gestational age.

But at 24 months, the babies fed preterm formula for up to six months after discharge had lower total fat mass compared to the babies who got the special formula only in the hospital (19.3% vs 21.7%; P < 0.01). They also had reduced trunk fat at 12 months (14.7% vs 16.9%; P < 0.005) and 24 months (14.1% vs 17.2%; P < 0.001).

"Interestingly," the study team notes, "these changes were not accompanied by changes in bone mineral density, bone mineral content or lean body mass." There were no between-group differences in these parameters at 12 or 24 months.

The post-discharge preterm formula group also had lower fasting insulin levels at 12 months (13.2% vs 17.2% mIU/L; P = 0.06) and at 24 months (13.6% vs 26.4%; P < 0.001), which supports the observation of decreased body fat in these infants.

"The results of this study are to our knowledge unique in evaluating the impact of a nutritional intervention with the prolonged use of premature formulas and the significant effects on body composition and fasting insulin, which may have important consequences in long term risks," Dr. Mericq noted in an e-mail to Reuters Health.

She also said, however, that longer term follow up of these children is needed to confirm whether the differences in the first year diet will ultimately positively impact body composition and fasting insulin as a surrogate of insulin sensitivity.

"This long-term follow up will also help to understand whether the changes will be permanent or will be overcome by exposure to high caloric foods after the second year of life. The results are nonetheless promising and suggest that a diet rich in docosahexaenoic acid may be beneficial for children with VLBW," Dr. Mericq said.

J Pediatr. Published online July 25, 2011.

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