Standardization of Warming Infant Feeds: Effect on Outcome

Sandy Sundquist Beauman, MSN, RNC-NIC / September 2016


The benefits of practice standardization in the hospital are well-documented. In the NICU, where vulnerable patients can be affected by the smallest inconsistencies, standardization can have perhaps an even larger impact on patient outcomes. While additional evidence is needed to support specific temperatures at which feeds should be delivered, it is impossible to draw any conclusions without standardization.  Once temperatures and method of warming are standardized, the benefits can be more easily evaluated.

Standardization of Practice

The literature is filled with benefits of standardization. Standardization is used to create the same outcome again and again, particularly when many people are involved, either in a single event or the same event many times.

Much has been borrowed from the airline industry regarding standardization. We are all thankful that there is a very specific safety checklist followed every time an airplane pilot prepares to take off, whether they have flown thousands, hundreds, or a handful of flights. Regardless of take offs being so common, we don’t hear “I do it all the time, I don’t have to think about it.”  Following the checklist may become more routine, but is still done.

Why Infant Feed Warming Should Be Standardized

The Human Milk Banking Association (HMBANA, 2011) advocates warming feeds to body temperature for premature infants, particularly those at risk for necrotizing enterocolitis (NEC).

Of course, HMBANA addresses the feeding of pumped breast milk. However, many feedings in the NICU are not breast milk for a variety of reasons. We know that NEC incidence is higher in infants who are fed cow’s milk based formula (Schanler, 2011). If warming of infant feeds truly has an effect on the incidence of NEC or even feeding intolerance, then all feeds should be warmed. Many formula feedings are fortified and prepared for 12 to 24 hours (refrigerated once mixed), so must also be warmed. Warming of feeds for near term and term infants may also be helpful when they are sick and in the NICU.

We now know that standardizing the progression of infant feedings decreases the incidence of NEC reportedly by as much as 75% (Smith, 2005; Hanson et al, 2011; McCallie et al, 2011; Patole&DeKlerk, 2005; Weidmeier et al, 2007). However, what the exact progression should be is not known. The references cited above do not have a common practice between units, but simply a common practice in feeding progression within a unit. Other practices, when standardized, have also resulted in improved outcomes.  Perhaps it’s not too much of a stretch to think that warming of milk could also be key in improving outcomes.

Let’s review the various practices to warm milk. The traditional method is to warm the milk in a container of warm water.  A couple of studies evaluated the temperature at which feeds were actually delivered using this warming method (Dumm et al, 2013, Lawlor-Klean, Lefaivor, Weisbrock, 2013).  Dumm et al demonstrated a range of milk temperature from 21.8°C to 36.2°C.  Lawlor-Klean, Lefaiver, Weisbrock (2013) demonstrated a range of milk temperature from 22°C to 46.4°C. Over-warming may lead to deterioration of some benefit from human milk. Over- or under-warming could also have impact on infant temperature.

How should milk warming be standardized?

Mechanical warmers serve as a standardization of temperature since the warming is pre-programmed specific to the volume of the milk.  We should create policies and standard practices for use of the mechanical warmer to include all feedings, both breast milk and formula, when used.

Feedings warmed to body temperature in the mechanical warmer cool off after a period of time if infused via pump.  So, for pump feedings, additional or continuous warming may be needed, particularly for the smallest infants and those at highest risk of feeding intolerance.  There is currently only one device on the market for this purpose.  Making this part of standardization for this specific population may be beneficial.

Finally, once a standard protocol has been created, implementation and auditing is important.  Successful implementation includes many avenues of teaching and learning.  While this is a simple practice, practice is hard to change. Without continual reinforcement, practices will slip back to the familiar. Reinforcement might include auditing the actual performance to ensure all feeds are warmed as per protocol on a specific day and time.

In addition, outcomes should be evaluated so that improvements can be shared with others.  Of course, in the case of performance improvement projects, the evidence cannot be generalized—but successful outcomes help encourage others to follow the practice carefully and evaluate their own outcomes.  Sharing successes is important even if only with your own medical and nursing staff. This further encourages the practice change.

Standardizing practices aid in predicting outcomes over time and also in determining variables that may lead to different outcomes. Once a warming protocol has been created, implemented, and outcomes monitored, individual cases of NEC may be evaluated to determine whether milk warming was used in that particular case as intended by the protocol.


Hanson C, Sundermeier J, Dugick L, Lyden E, Anderson-Berry AL.Implementation, process, and outcomes of nutrition best practicesfor infants 1500 g. NutrClinPract. 2011;26(5):614-624.

McCallie KR, Lee HC, Mayer O, Cohen RS, Hintz SR, Rhine WD.Improved outcomes with a standardized feeding protocol for very lowbirth weight infants.J Perinatol. 2011;31(Suppl 1):S61-S67

Patole SK, de Klerk N.  Impact of standardised feeding regimens on incidence of neonatal necrotisingenterocolitis: a systematic review and meta-analysis of observational studies.  Arch Dis Child Fetal Neonatal Ed 2005;90:F147–F151.

Schanler R. Outcomes of human milk-fed premature infants.SemPerinatol. 2011;35(1):29-33

Smith JR. Early enteral feeding for the very low birth weight infant:the development and impact of a research-based guideline. NeonatalNetw. 2005;24(4):9-19.

The Human Milk Banking Association of North America, Inc. (2011).Best Practice for Expressing, Storing and Handling Human Milk in Hospitals, Homes and Child Care Settings. HMBANA: West Hartford, CT.

Wiedmeier SE, Henry E, Baer VL, Stoddard RA, Eggert LD, Lambert DK, Christensen RD.  Center differences in NEC within one health-care system may depend on feeding protocol.  American Journal of Perinatology.  2008;25(1):5-11.


About the Author

Sandy Sundquist Beauman has over 30 years of experience in neonatal nursing. In addition to her clinical work, she is very active in the National Association of Neonatal Nurses, has authored or edited several journal articles and book chapters, and speaks nationally on a variety of neonatal topics. She currently works in a research capacity to improve healthcare for neonates. Sandy is also a clinical consultant with Medela. You can find more information about Sandy and her work and interests at