Bottle Warmers come in all shapes and sizes and use different methods to actually warm your baby's meal.
One important factor every mother should know is to never use the microwave to heat your baby's milk. The high heat of a microwave can not only cause dangerous "hot-spots" in the milk but, with regard to breast milk, can also result in a deterioration of nutrients and other beneficial qualities important for your baby's health and immunity.
What we found to be incredibly surprising in our warmer testing was that, not unlike the microwave, most of the bottle warmers we tested make it far too easy to overheat breast milk, which results in a significant loss of nutritional and immunological quality. For more on this we urge you to refer to our article Best Practices for Handling Breast Milk.
Alas, in our mission to help parents find the best, we put seven of the most popular bottle warmers to use and rated them based on our side-by-side comparisons. We noted which features worked great for us and which we'd rather not have to deal with. Based on our experiences, here's a run down of what we feel makes a bottle warmer a worthy investment.
Health and Safety
As stated previously, we looked closely at the method used to heat the bottle (steam vs. water bath) and the temperatures the bottle was submitted to during warming. Some of the steam warmers pushed temperatures up to 199 degrees F (93 C), which in our opinion, is way too hot to safely warm baby's milk, especially breast milk. When breast milk is submitted to high temperatures, many of it's health and protective qualities are damaged. Based on our findings, we don't recommend using plastic storage bags in a steam warmer, and would encourage that frozen breast milk be thawed overnight in the refrigerator before heating. This allows it to be exposed to less time in the warmer.
Please read our article Best Practices for Handling Breast Milk for more on this important topic.
Since a bottle warmers main purpose is to provide your baby with a comfortably warm meal, this was first priority in our testing.Dr. Brown's Deluxe Bottle Warmer and the Munchkin Precision Digital scored well in this area, producing a consistently warmed bottle with each use (yet even these warmers run at warming bath temperatures we believe are too hot to fully preserve breast milk quality). Others, like the First Years Quick Serve varied in their results, sometimes leaving us with in an overly hot or still cool bottle. We'd have to run it through a second, and in some cases a third, warming cycle which was frustrating. Your time is precious and we believe your bottle warmer should be capable of getting the job done consistently right on the first try.
Before a bottle warmer can fit seamlessly in to your routine, you have to learn how to use it. Out of the box, the warmers we tested included a wide variety of "parts". Ranging from one solid unit like the Kiinde Kozii to a unit plus eight extra pieces to figure out, like The First Years Nursery Bottle Warmer you can have a quite a task on your hands. The easiest to use warmer in our testing was the Editor's Choice Award winning Kiinde Kozii scoring a 9 out of 10. The Munchkin Precision Digital and the Dr. Brown's Deluxe Bottle Warmer, followed close behind at 8 out of 10 and 7 out of 10, respectively.
On top of assembly, there are charts included with each unit to help figure out warming times and these ranged from simple to complicated as well. (Think total overload with the First Years Nursery Bottle Warmer and First Years Quick Serve instructions, pictured at right).
You'll also want to think about the type of bottle you'll be using. Some of the warmers (Dr. Brown's Deluxe Bottle Warmer) didn't fit the extra-wide based bottles like Tommee Tippee or Comotomo. If you're using larger 8 oz. bottles, investing in a full size warmer might be to your advantage, as it should house them a little better.Munchkin Time Saver.
Another consideration we'd like to bring up is the recommended wait time for a unit to run a warming cycle consecutively. Being able to start another cycle immediately would be very important if you were heating two or more bottles in a row, say for twins. It's also handy if the first cycle doesn't quite get the milk warm enough. Most of the warmers we tested could be run again immediately, or at least within a few minutes. The longest wait time was 10 minutes between, and this was with The First Years Nursery Bottle Warmer and The First Years Quick Serve.
A few other features we appreciate is when a warmer has a timer that signals the end of warming with an audible beep. Additionally, we feel that an auto-safety shut-off feature is very important. The Philips AVENT Express had neither and its poor health/safety scoring is due to these very details. It is easy to get side tracked with baby while a bottle is warming. All but one of the warmers we tested turned itself off automatically. In many of the warmers we tested, warmed milk's temperature will continue to rise if the bottle is left in the warmer after it has reached "doneness" (ideally body temperature 98.6F/37C), often to the point where reverse steps then need to be taken to cool the bottle down in order to feed baby. Additionally, the healthful qualities of breast milk begin to degrade at temperatures starting around 104-113F/40-45C, so removing a bottle promptly when done is important both for health and safety reasons.
Lastly, we wanted to look at how easy each unit would be to clean. Although this isn't a per-use or even daily requirement, there is a certain aspect involved when it comes to cleaning a bottle warmer, and we found, that unless you spill milk on the unit, this really comes down to proper maintenance. Since bottle warmers use water in some form or another to warm a bottle, the issue seems to be mineral deposits forming someplace on the unit.
We hope that the addition of a bottle warmer to your personal baby gear line-up will help things run a little more smoothly at your house. Although it may take a few tries to get to that perfect setting, once you're there, your warmer should perform consistently and make life with baby just that much easier!