Human milk, fortification and preterm nutrition

Clinical Case

History

This former 27-week gestation female infant was born at 780 g to a 34-year-old primigravida following preterm prelabour rupture of membranes with histological chorioamnionitis. She required initial continuous positive airway pressure and one dose of surfactant for respiratory distress syndrome. Enteral feeds of expressed breast milk were started on day two and advanced to full enteral feeds by day ten. Standard bovine multicomponent fortifier was introduced at 100 mL/kg per day. Her NICU course was complicated by a patent ductus arteriosus treated with ibuprofen and late-onset sepsis at day eighteen, during which feeds were held for 48 hours. Mother's own milk supply has been maintained throughout [1].

Examination at 36 weeks PMA

The infant is clinically stable in room air, taking 150 mL/kg per day of fortified mother's milk at 24 kcal per ounce. Weight is 1950 g, between the 3rd and 10th centile on the Fenton chart. Head circumference is 30.5 cm, just below the 3rd centile. Weekly weight gain over the last two weeks has been 9 g/kg per day, below the target of 15 to 20 g/kg per day. Head circumference velocity is 0.6 cm per week, below the target of 0.9 cm. The abdomen is soft with no distension. Tone and reflexes are normal for corrected age [1].

Key Questions

1. What is this infant's nutritional status and what is the problem? She has extrauterine growth restriction, with weight and head circumference tracking below the 10th centile at 36 weeks postmenstrual age. Her weight velocity of 9 g/kg per day and head circumference velocity of 0.6 cm per week are both below the intrauterine rate targets of 15 to 20 g/kg per day and 0.9 cm per week respectively. This growth failure, particularly the lagging head growth, places her at increased risk of adverse neurodevelopmental outcomes including cognitive impairment [1].

2. What is the target nutritional intake, and is she meeting it? The ESPGHAN targets are 110 to 135 kcal/kg per day of energy and 3.5 to 4 g/kg per day of protein. At 150 mL/kg per day of 24 kcal per ounce fortified milk, she is receiving approximately 120 kcal/kg per day, which is adequate for energy. However, the poor growth suggests either higher metabolic demand or inadequate protein. The blood urea nitrogen should be checked; if it is below 1.5 mmol/L, protein intake is inadequate and adjustable fortification should be initiated [2].

3. How would you escalate the fortification strategy? I would increase caloric density to 26 or 30 kcal per ounce using additional fortifier or modular fat and carbohydrate supplements. I would implement adjustable fortification, adding extra protein titrated to maintain blood urea nitrogen above 1.5 mmol/L. If available, I would consider targeted or individualised fortification, in which the actual macronutrient content of her mother's milk is analysed and individualised modules added to meet exact protein and energy targets [2].

4. What are the key principles to preserve in her feeding plan? Mother's own milk must remain the substrate throughout, because its immunological and trophic properties protect against necrotising enterocolitis and promote gut maturation. The Lucas and Cole data established that human milk halves NEC compared with formula, and this protective effect must not be sacrificed by switching to formula in pursuit of growth. Fortification intensifies the milk while preserving its biological benefits [3].