Neonatal Nutrition 🍼

I’ll be honest—nutrition has always been one of the NICU topics I’ve struggled with. But since May is NEC Awareness Month, it felt like the perfect time to revisit this critical subject.

I once heard a speaker at a conference say, “Prematurity is a nutritional emergency.” That line hit me hard—and it’s stuck with me ever since.

When babies are born prematurely, they’re abruptly separated from the carefully calibrated nutritional environment of the womb. In those final weeks of pregnancy, the fetus is busy stockpiling essential nutrients like iron, calcium, fat, and glycogen. When that process is cut short, these babies enter the world in a state of nutritional crisis.

Framing prematurity as a nutritional emergency helped me understand its urgency in a whole new way. I’ve always known nutrition is important—but when you're juggling respiratory support, hemodynamic instability, infection risk, and family needs, it’s easy for nutrition to slip down the priority list.

But without precise, intentional nutritional support, our most vulnerable patients face serious risks, including:

• Growth failure

• Delayed gastrointestinal development

• Compromised neurological progression

• Metabolic instability

• Long-term health complications

We now recognize that enteral feeding isn’t just about providing nutrition—it’s a vital developmental intervention. Every feed is a carefully timed opportunity to support the preterm infant’s transition from intrauterine to extrauterine life.

Here’s how each feed supports key physiologic systems:

• Gastrointestinal maturation: Early trophic feeds ("gut priming") stimulate gut motility, hormone secretion, and enzyme activity. They help prepare the immature GI tract for full enteral feeds, reduce intestinal permeability, and promote intestinal barrier integrity.

• Immune system priming: Human milk is rich in bioactive components—like secretory IgA, lactoferrin, lysozyme, and human milk oligosaccharides (HMOs)—that help shape the neonatal immune response and establish a healthy gut microbiome (one of my favorite topics). This immunologic training starts with the very first drops of milk.

• Metabolic stabilization: Feeding promotes glucose homeostasis, prevents catabolism, and supports appropriate weight gain. It also allows for the gradual transition from parenteral to enteral nutrition, reducing risks associated with prolonged TPN (like cholestasis or electrolyte imbalances).

• Infection prevention: The gut plays a major role in protecting against infection. A well-fed gut—with the support of human milk—reduces translocation of harmful bacteria, supports beneficial flora, and lowers the risk of complications like NEC and late-onset sepsis.

• Neurological development: Nutrition fuels brain growth, especially during the third trimester when cortical folding and myelination accelerate. DHA, choline, and other nutrients in human milk play a direct role in synaptogenesis and neuroprotection.

As we move beyond the “why” of feeding, we also need to focus on the “what.” Feeding isn’t just about volume—it’s about composition. The right balance of macronutrients gives preterm infants the raw materials they need to survive and thrive. Let’s break it down:

Protein 💪

For preterm infants, protein isn’t just a growth nutrient—it’s a metabolic necessity. Unlike term infants who have time to build glycogen and fat reserves in utero, preterm infants are born with minimal energy stores.

Without a steady supply of protein:

• Muscle tissue begins to break down (catabolism)

• The body converts muscle proteins into glucose to meet energy needs

• Growth and repair processes are disrupted

Protein is a multipurpose molecule, essential for:

• Building lean body mass

• Preventing muscle breakdown

• Producing enzymes and hormones

• Supporting immune function

• Driving tissue regeneration and organ development

🧪 Recommended intake: Preterm infants typically require 3–4.3 g/kg/day—nearly double the amount needed by term infants (2–2.5 g/kg/day)—to support rapid tissue growth and metabolic stability.

Fats 🧠

Fats do more than provide calories—they shape the developing brain, retina, and cell membranes.

Preterm infants miss out on the third-trimester fat deposition that normally supplies DHA, ARA, and other key lipids for neurologic development. This makes postnatal fat delivery absolutely essential.

Important fat considerations in preterm nutrition:

• Medium-chain triglycerides (MCTs): Easier to absorb and metabolize in immature guts

• DHA and ARA: Vital for myelination, visual development, and cognitive outcomes

• Human milk enzymes: Support fat digestion even when the infant’s gut isn’t fully ready

🎯 The goal isn’t just energy—it’s targeted fat delivery to meet neurodevelopmental needs.

🧪 Recommended intake: Preterm infants often need 4-7 g/kg/day of fat (compared to 3.3–6 g/kg/day for term infants) to account for the decreased intestinal fat digestion and absorption.

Carbohydrates ⚖️

Glucose is the primary energy source for the neonatal brain—but in preterm infants, it’s all about balance. Immature glucose regulation makes them vulnerable to both hypoglycemia and hyperglycemia, each with potential neurologic consequences.

Carbohydrate metabolism in preterms is nuanced:

• Limited glycogen stores mean they rely heavily on exogenous glucose

• Immature insulin response can lead to blood sugar fluctuations

• Excessive glucose can contribute to fat deposition in the liver, metabolic stress, or increased CO₂ production.

In the NICU, we balance carbohydrate intake with:

• Regular blood glucose monitoring

• Gradual advancement of enteral feeds

• Adjustments in TPN based on clinical status and metabolic tolerance

🧪 Recommended intake: Carbohydrates typically make up 40–60% of total calories (~12-14g/kg/d), but the exact dosing must be tailored to each infant’s tolerance and metabolic state.

The typical glucose utilization in a healthy term infant ranges from 4–6 g/kg/min, in preterm infants, that seemingly simple number becomes a complex clinical challenge due to:

• Immature hepatic glycogen stores

• Limited gluconeogenic capacity

• High cerebral glucose demands

• Increased metabolic stress

• Poorly regulated insulin secretion and sensitivity

Understanding the Glucose Infusion Rate (GIR)

The Glucose Infusion Rate (GIR) refers to the amount of glucose delivered per kilogram of body weight per minute, usually expressed in mg/kg/min. It helps the NICU team balance the energy needs of the preterm infant while avoiding harmful blood sugar extremes.

GIR = (Dextrose containing Total Fluids in mL/kg/day x 0.69) x Dextrose%

In clinical practice, our goals are to:

• ✅ Prevent hypoglycemia, which can cause brain injury or developmental delays

• ✅ Avoid hyperglycemia, which contributes to osmotic diuresis, metabolic derangements, and increased risk of infection

• ✅ Support adequate caloric intake for growth and healing

Typical Glucose Infusion Strategies in the NICU

• 🍼 Initial dextrose concentrations: Typically start at 10–12.5% Dextrose (D10–D12.5)

• ⚖️ Target GIR: Often 4–8 mg/kg/min, titrated up or down depending on tolerance

• 🩸 Frequent monitoring: Point-of-care glucose monitoring to assess trends and tailor interventions

  • I've seen studies using continuous glucose monitoring in term babies! I wonder if/when we will see CGM in preemies? Imagine all the heelsticks we could avoid!

• 🔁 Individualized response: Adjustments based on concurrent stressors, feeding tolerance, illness severity, and TPN components

Hyperglycemia: A Common and Complex Complication

Despite careful glucose delivery, hyperglycemia remains common in the preterm population, particularly in the first days of life. Contributing factors include:

• Immature insulin response

• Transient insulin resistance

• Surges of stress hormones (like cortisol and catecholamines)

• Excessive glucose delivery in TPN or during critical illness

Risks of sustained hyperglycemia include:

• 🚱 Osmotic diuresis → Dehydration and electrolyte loss

• ⚡️ Increased metabolic demand → Caloric wastage

• 🧠 Potential neurodevelopmental impact → Altered brain growth and long-term programming

• 💉 Increased infection risk → Possibly due to immune suppression

Clinical Takeaway: Precision + Individualization

No two preterm infants metabolize glucose the same way. Effective glucose management requires a dynamic, individualized approach that considers:

• Continuous glucose levels and trends

• Weight changes and fluid status

• Concurrent therapies (e.g., steroids, pressors, feeds)

• Evolving tolerance to enteral nutrition

• Integration with total parenteral nutrition (TPN) plans

Why This Matters

Managing glucose in the NICU isn’t just about meeting a number. It’s about supporting metabolic integrity during a critical window of brain and body development. Every adjustment to the GIR is an opportunity to:

• Protect the brain

• Preserve lean body mass

• Prevent complications

• Promote long-term growth and developmental outcomes

Let's Practice GIR Together

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If nutrition hasn’t always felt like your favorite topic, you’re not alone—it took me years to fully appreciate its depth and power. But now I see every feed, every TPN adjustment, every calculated gram of protein or fat as an investment in a baby’s future. You are literally helping to build brains, protect guts, and fuel healing. That’s incredible.

Thank you for being the kind of nurse who keeps learning, who shows up for the tiniest patients, and who understands that the details matter—even the ones we can’t always see.

I’d love to know—what’s something new you learned about neonatal nutrition this month? Or something you want to dive deeper into? Just hit reply and let me know. I read every message and love hearing from you.

Until next time,
Amanda 💛
Your NICU CNS + Study Buddy

References

Fanaroff, et al., Klaus & Fanaroff's Care of the High-Risk Neonate, Elsevier-Saunders, 2019.

Gardner, et al., Handbook of Neonatal Intensive Care: An Interprofessional Approach, Elsevier, 2021.

Verklan, et al., Core Curriculum for Neonatal Intensive Care Nursing, Elsevier, 2021.

Stark, et al., Cloherty and Stark’s Manual of Neonatal Care 8th ed., Wolters Kluwer, 2017.

Carlson, C. & Shirland, L. (2020). Neonatal Parenteral & Enteral Nutrition: A resource guide for the novice and student Neonatal Nurse Practitioner. NANN

Martin, et al. Fanaroff and Martin’s Neonatal-Perinatal Medicine: Diseases of the Fetus and Infant, Elsevier, 2020.

Gomella, Neonatology, 8th ed., Lange, 2020.

McGrath, J., Medoff-Cooper, B., Darcy-Mahoney, A., McGlothen-Bell, K., Velasquez, A. (2023) Oral Feeding and the High Risk Infant in Developmental Care of Newborns & Infants. NANN

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