Infants often prefer milk at body temperature, and for many people the easiest way to heat it is in a microwave oven. Yet parents are widely warned against heating milk this way:

To ensure that the feed heats evenly, periodically shake or swirl the feed in its covered container. Note: microwave ovens should never be used for re-warming feeds as uneven heating may result in 'hot spots' that may scald the infant's mouth.   —WHO

Or:

Do not use microwave ovens to heat bottles, because they do not heat them evenly. Uneven heating can scald your baby or damage the milk. Bottles can also explode if left in the microwave too long. Excessive heat can destroy important proteins and vitamins in the milk.   —American Academy of Pediatrics: New Mother's Guide to Breastfeeding [1]

Yes, you don't want to feed your baby milk that's too hot, and you don't want to habitually feed them milk that's been overheated, but using the microwave is completely safe as long as you (1) use a glass bottle with no lid, (2) swirl the bottle after heating, and (3) test a drop on your wrist before giving it to the baby. Milk that's the right temperature should feel like nothing, or very slightly warm. If it feels actually warm, cool it off holding the bottle under the tap and don't heat it as long next time.

Because the microwave can heat the milk but not the glass, it's best to heat the milk most of the way to the temperature you want, swirl it, and then put it in for the rest of the time. This avoids overheating the milk. When you're first learning how quickly your microwave heats things, try just a few seconds per ounce of milk; we're talking about very small amounts of stuff to be heated.

Recommendations against microwaving have minimal safety benefits and waste millions of people's time and hot water.

(Earlier, less strident post.)

[1] The CDC recommendation is just a quote of this AAP recommendation.