July 17, 2018
6 min read

Growth of preterm neonates optimized with enhanced nutrition

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Proper maternal nutrition is essential to child growth in utero, where the placenta provides a continuous source of protein, calories and various nutrients for the developing fetus. This nutrition promotes adequate growth of bone, muscle and internal organs, including the digestive and nervous systems.

Preterm birth immediately cuts the neonate off from this source of nutrition, impeding development. This leaves NICU providers to replace nutrition that would have been received from the infant’s mother, with pediatricians left to direct this process once the infant is discharged. After discharge, communication between all care providers, including pediatricians, NICU staff, social workers and others, should be stressed to ensure optimal development.

“The third trimester is a time when a lot of growth occurs, and fetuses go from being about 500 g to about 3,500 g,” Michael K. Georgieff, MD, professor in the department of pediatrics at the University of Minnesota Medical School and neonatologist at the University of Minnesota Health, told Infectious Diseases in Children. “The responsibility and the challenge for neonatologists and people taking care of these babies is to get them to grow.”

Victoria Catalano

“The AAP is pretty clear that they want the babies to grow in the way that they would have grown if they were a fetus in utero,” he continued. “That has proven to be an enormous challenge. There are just so many things working against them.”

Timing of nutrition

Once a child is born, nutrition to promote development should begin as soon as possible. Unfortunately, many children born prematurely are not able to tolerate feeds due to an underdeveloped digestive system, respiratory support needs and other critical care they receive. Current best practice is to provide preterm infants — especially very-low-birth-weight infants — a parenteral source of energy and protein soon after birth.

“One challenge that we face with nutrition early on is tolerance,” Sara Ramel, MD, associate professor at the University of Minnesota Medical School and neonatologist with the University of Minnesota Health, said in an interview. “The baby’s blood sugar or lipid levels may become too high from the delivery of nutrition through an IV.”

“Being clinically stable enough to tolerate enteral feeds can also be a challenge,” she added. “Some of our babies have low blood pressure, infections or a lot of respiratory support needs that limit their ability to get all their nutrition through their intestines. We are then forced to use their IV at that point. At discharge, the challenge is balancing the benefits of the baby breastfeeding and getting their mom’s milk with making sure they get enough nutrition.”

Michael Georgieff

According to a study published in The British Journal of Nutrition, low-birth-weight infants do not receive adequate nutrients and protein from breast milk alone. The authors recommended using a fortifier, which adds up to 1.3 g of protein for every 100 mL of breast milk for small infants. This process can begin once the preterm infant can tolerate between 50 mL and 70 mL/kg daily.

“We generally see readiness [to begin oral feedings] around 34 weeks’ gestation, and we look for the ability to coordinate suck, swallow and breathe capabilities, which are the three things anyone needs to eat successfully,” Victoria Catalano, RDN, LD, CNSC, CLC, NICU dietitian the Children’s National Health System, told Infectious Diseases in Children.

Catalano said that an important nutritional need that fortification addresses is protein, which is crucial to developing brain tissue and lean body mass like bone and muscle. She added that preterm neonates have small amounts of skeletal muscle. The addition of fortification to human milk or formula can increase their chances of proper development.

For preterm neonates who are not breastfed, post-discharge formulas specifically designed for the nutritional needs of this population are available. Compared with formula made for term infants, which includes 66 to 68 kcal/100 mL and 1.4 to 1.7 g/100 mL of protein, post-discharge formula can include roughly 72 to 74 kcal/100 mL and between 1.8 and 1.9 g/100 mL of protein. These formulas also include varying ranges of minerals, vitamins and micronutrients.

A commentary released by the European Society for Pediatric Gastroenterology, Hepatology and Nutrition Committee on Nutrition suggests that infants who are fed a post-discharge formula should remain on this diet for 3 to 12 months.

“It takes some time — usually after 4 months post-discharge — before we would start transitioning the kids over to straight breast milk or formula without fortification,” Georgieff said. “I see a lot of patients in my clinic discontinuing the fortification too early because pediatricians are not comfortable with formulations or people get tired of fortifying. We do not want parents to stop fortification until their child is caught up on their growth.”

Ramel warned that children who do not receive adequate nutrition during this critical time may lose ground in weight, head growth and length, which may take several years to catch up to a typical size. These children also may have negative neurodevelopmental and metabolic outcomes. Because of these concerns, she stressed that collaborative effort between the NICU, pediatricians and other care providers is necessary to ensure that enough nourishment and care is received.


Transferring care

According to Catalano, nutrition may be the most collaborative part of a preterm neonate’s health care.

Sara Ramel

“We put a large emphasis on [nutrition], and we talk about whether these babies are meeting protein and calorie goals every day,” she said. “Case management and social workers are very involved in any sort of training needed to discharge the baby, and collaboration occurs with home care companies and the pediatrician to make sure that the parents are set up for their nutrition plan. We in the NICU always encourage pediatricians to call us. It is very much full circle and collaborative.”

Georgieff also stressed the importance of collaboration between the pediatrician and NICU staff.

“Pediatricians and NICU follow-up clinics, if available, should work closely together to monitor nutrition and growth of these babies,” he said. “Once the child has reached 50 weeks postconceptional age — 10 weeks past term equivalent — we transition them over to the WHO growth curves, which are derived from how breastfed babies around the world grow.”

WHO growth curves are applicable to children between the ages of 0 and 2 years and account for longitudinal length and weight. The norms set by these curves are based on the optimal growth of children who were mainly breastfed for a minimum of 4 months and continued to breastfeed at 12 months.

Georgieff recommended that when pediatricians are assessing the growth of their premature patients based on the WHO growth curves, they should use the child’s corrected gestational age. He also suggested that fortification should not be discontinued before 4 months’ corrected age unless the child has exceeded the 50th percentile for their corrected age.

Although transitioning from the NICU to the pediatrician’s office, from parenteral to enteral, and then from fortified to unfortified nutrition can be a long process, optimal nutrition can provide these preterm infants the opportunity to catch up developmentally with their peers. Pediatricians, according to Ramel, are a critical component to continuing the care necessary to provide the best possible outcomes for these at-risk neonates.

“We really think that the key window for catching up on growth to optimize their neurodevelopmental outcomes extends to about 4 months’ corrected age,” she said. “Optimizing their nutrition early, like while they are in the NICU right after they are born and before going home, is important. If we are not able to optimize their growth then, pediatricians should continue to focus on making sure that the child is getting good nutrition and growing well in early infancy after discharge.” – by Katherine Bortz


Disclosures: Catalano, Georgieff and Ramel report no relevant financial disclosures.