Milk is an ideal breeding ground for bacteria, so if even a few get into your baby’s milk, they can multiply rapidly. That is why you need to be so much more fussy about the hygiene of your baby’s bottles than the hygiene of anything else she puts into her mouth, like her hands or toys. There may be bacteria on those too, but they won’t be multiplying.
Her body can cope with a few, but the millions in an ill-washed bottle made a couple of hours ago may make her very ill.
If you put sterile milk into sterile bottles, keep it cold until it’s needed, and feed it to the baby the moment it’s being warmed. Any bacteria that may get on to the nipple, from your hands or her own mouth, will have no time to multiply. Do throw away any milk she leaves, though. If you save that warm bottle, complete with those few bacteria for another time, and pour the remaining milk back into the jug of sterile milk in the refrigerator, you’re undoing all of your own work.
Sterilize and wash bottles, nipples, caps, etc. by boiling them, fully submerged, for ten minutes. Boil the water you’ve used to mix the feeding. Open milk cans with an opener again, especially for that purpose, and wash your hands first.
Cap the bottles and refrigerate them the moment they’re filled, and you can safely keep them for at least twenty four hours.
Penelope Leach, Ph.D., is one of the world’s most respected (and best-loved) developmental child psychologists. She is most widely known for her best-selling books on child development and parenting. They include Babyhood, Children First: What Society Must Do — and Is Not Doing — for Our Children Today, the classic Your Baby & Child: From Birth to Age Five (now in a new edition for a new generation), and Your Growing Child: From Babyhood Through Adolescence.
