When babies are born prematurely, their immediate challenges for survival are their lungs' ability to effectively inhale oxygen and exhale carbon dioxide and their hearts' ability to effectively pump blood to and from their vital organs. These necessities determine many of the complications and triumphs of the earliest hours and days. The technology of neonatal care has dramatically improved quality survival in the preterm, very low birth weight (under 1750 grams or 3 lbs 14 ounces) infant.
A new study from France, published in the November, 2008 issue of The Journal of Pediatrics, adds to the resources doctors have by showing that giving preemies an enhanced formula for the first two months can offer the long-term benefits of stronger bones and better physical development.
Once a premature infant's condition has been stabilized, he or she must take in nutrition that it would normally still be receiving via the maternal placenta in order to continue successful growth and development. The ability to absorb nutrients, digest them into useable building blocks, metabolize them into necessary forms, and excrete waste products all depend on the newborn's premature digestive, filtering, and excretory systems. The nutritional challenges offered to these yet immature organs are different than those faced by full term infants, and optimal nutrition of premature infants has been an area of considerable research.
Although premature infants' bones grow in length and circumference, the quality of the bones themselves is often poor..
The impact of prematurity and its complications can last a lifetime. Organ-system function, neurodevelopmental function, as well as ultimate height, weight and head circumference, are influenced by the earliest months. The impact of prematurity is even seen in adult health. Studies have noted increased risks for coronary events and insulin resistance in adults who were small from birth through two years and then experienced rapid "catch up" weight gain. This suggests that getting on a good and consistent growth track as early as possible is a potentially healthier strategy.
The new French study focuses on the impact of prematurity on infant bone quality and adds to the literature on the optimum timing for nutritional interventions. Although premature infants' bones grow in length and circumference, the quality of the bones themselves is often poor because they lack the normal mineral density seen with adequate mineral content. This is termed "relative osteopenia", or thin bones and can lead to significant structural vulnerability and weakness throughout the skeletal structure. This is probably a result of the premature infants' inability to absorb and use calcium, phosphorous and other bone building blocks as effectively as full-term babies can.
The studied intervention was a special premature formula (PF), which was started when the premature infants were ready to be discharged from the hospital. The preterm formula had 35% more protein, 21% more energy, 96% more calcium and 89% more phosphorus than the regular, full-term formula.
Forty-nine infants, who were born at least 7 weeks early, weighed less than 1750 grams, had no birth defects, and had similar hospital courses, were recruited into the study. From the time of discharge, and for the next two months, half the infants were fed the enriched preterm formula and half were fed the term formula. At the end of the first two month feeding period, all infants were changed to an exclusive diet of the term formula At the end of the second two month period (four months from hospital discharge), the feeding regimen was unrestricted but the infants all continued on the term formula.
The premature infants' body weight, length, head circumference and bone mineral content and density were measured at two, four, and 12 months corrected age (meaning, a baby born 3 months early would be 12 months old at 15 months). At each measurement period, bone mineral content and growth were significantly greater in the preterm infants fed PF for the first two months than those fed the standard formula. Additionally, their bones were more densely mineralized, rather than simply being longer. There was no difference in the fat mass between the two feeding groups.
The study also demonstrated that nutritional supplementation of preterm infants with the PF was especially beneficial to male infants. This is consistent with previously recognized observations that early nutritional interventions on growth and neurodevelopmental outcome are greater in preterm boys as compared with preterm girls.
As premature, very low birth-weight infants are surviving their earliest challenges, the management of their continued development outside the uterus remains an area of critically important research. When their preemies are discharged from the hospital, parents of preemies may wish to consult with the specialists who have been caring for them regarding feeding recommendations and appropriate follow up of growth, development, and bone strength.