3.2 Milk Handling, Storage, Donor Milk & Fortification

Safe Handling and Storage of Expressed Human Milk

Storage time limits from the Centers for Disease Control and Prevention (CDC) and the Academy of Breastfeeding Medicine (ABM) are classic exam material. Times are cumulative — count from expression, and use the oldest milk first.

Additional handling rules that appear as distractors:

• Never microwave human milk — microwaving creates hot spots that scald the infant and destroys immune components. Warm under warm running water or in a bottle warmer; swirl gently to mix the fat layer.
• Do not add warm freshly expressed milk directly on top of already frozen milk in the same container; chill fresh milk before combining.
• Label every container with the infant's name, date, and time of expression.

Pumping and hygiene guidance

Wash hands before pumping. Clean all pump kit parts that contact milk after each use; for infants under 2 months, preterm, or immunocompromised, the CDC recommends daily sanitizing (boiling, steam, or dishwasher with heated dry) in addition to washing. Allow parts to air-dry completely — damp parts breed organisms. Hospital-grade multi-user pumps require a personal kit for each user.

Pasteurized Donor Human Milk

When mother's own milk (MOM) is unavailable or insufficient, the recommended alternative for high-risk infants is pasteurized donor human milk (PDHM) from a bank following Human Milk Banking Association of North America (HMBANA) standards:

• Donor screening: Detailed health history plus serologic testing for HIV-1/2, HTLV-I/II, hepatitis B, hepatitis C, and syphilis; donors defer for high-risk behaviors and most medications.
• Holder pasteurization: Milk is pooled and heated to 62.5 degrees C for 30 minutes, then rapidly cooled. Post-pasteurization bacterial cultures must show no growth before dispensation.
• Effect on bioactive components: Pasteurization eliminates bacteria and cytomegalovirus (CMV) but partially degrades heat-labile factors — secretory IgA is substantially reduced, lactoferrin and bile salt-stimulated lipase are largely inactivated, and lysozyme is partially reduced. Oligosaccharides and most macronutrients are largely preserved.
• Indications: Primarily preterm and very low birth weight (VLBW, under 1,500 g) infants when MOM is unavailable; some centers extend use to short bowel syndrome, post-surgical feeding intolerance, and immunodeficiency.
• NEC reduction: Meta-analyses show formula feeding approximately doubles the risk of necrotizing enterocolitis (NEC) compared with donor milk in preterm infants, supporting an exclusive human milk diet in this population. A trade-off is slower growth with unfortified donor milk because of its lower protein content.
• The AAP discourages informal (peer-to-peer) milk sharing because of contamination, CMV transmission, and medication exposure risks.

Fortification of Human Milk for Preterm Infants

Unfortified human milk — even preterm mother's milk — cannot meet preterm requirements for protein, calcium, phosphorus, sodium, and energy after the first weeks. Multicomponent human milk fortifier (HMF) is added to address this:

• Timing: Fortification is typically initiated when enteral intake reaches about 50-100 mL/kg/day (many units start near 80-100 mL/kg/day).
• Products: Standard bovine-based fortifiers (powder or liquid) raise milk to 22-24 kcal/oz and add protein, calcium, phosphorus, and vitamins. Human milk-derived fortifiers (processed donor milk products) permit an exclusive human milk diet, with some trials showing lower NEC rates; cost and availability limit use.
• Targets: Roughly 3.5-4.5 g/kg/day of protein (ESPGHAN suggests 4.0-4.5 g/kg/day for infants under 1 kg and 3.5-4.0 g/kg/day for those 1-1.8 kg), with calcium about 120-200 mg/kg/day and phosphorus 70-115 mg/kg/day. Adjustable and targeted fortification strategies individualize protein delivery using BUN or milk analysis.
• Monitoring: Track weight, length, head circumference, BUN, and alkaline phosphatase — a high alkaline phosphatase with low phosphorus signals metabolic bone disease and prompts increased mineral and vitamin D delivery.
• Risks and traps: Fortification raises osmolality, so milk should be fortified close to feeding time. Powdered fortifiers are not sterile — handle aseptically because of Cronobacter sakazakii risk, use single-patient containers, and respect hang-time limits (commonly 4 hours for fortified milk). Preterm breastfed infants also need enteral iron of about 2 mg/kg/day started at roughly 4-6 weeks of age, plus vitamin D - ESPGHAN supports 400-1,000 IU/day for the hospitalized preterm infant, while AAP guidance uses 200-400 IU/day until the infant exceeds 1,500 g and then 400 IU/day.

Caloric Density: The kcal/oz Concept

Standard term human milk provides about 19-20 kcal per ounce (~67 kcal/100 mL). In-hospital preterm feeds are usually fortified to 24 kcal/oz, and discharge plans typically use 22-24 kcal/oz. The math is conceptual: each packet or measured dose of fortifier contributes a defined calorie and nutrient increment to a defined milk volume, so the final density equals base calories plus additive calories divided by final volume. Routine densities above 24-30 kcal/oz raise osmolality and renal solute load and require dietitian supervision.

NICU Milk-Handling Safety Systems

Misadministration — giving one mother's milk to another infant — is treated as an exposure event: the source mother is tested (HIV, hepatitis B and C) and the recipient is counseled and followed, though transmission risk from a single exposure is low. Prevention systems include bar-code scanning of expressed milk matched to the infant, two-identifier verification, dedicated milk-handling technicians, centralized preparation rooms, and standardized labels showing infant identifiers, expression date/time, and additives.

High-yield handling errors (exam traps): refreezing thawed milk, microwaving, storing milk in the refrigerator door, topping off frozen milk with warm fresh milk, prolonged hang times, and fortifying milk hours before feeding.