Can My Baby Wean Before One Year?

My 10-month-old is weaning off formula by herself. I’ve tried hiding it in food and switching it to an open cup and to a straw cup. She just doesn’t want it anymore. She eats three full, balanced meals a day with plenty of dairy sources. Is it okay to switch to cow’s milk? She is in the 92nd percentile for weight and the 100th for height.
—Meagan

This question gets at what I think is a deep and confusing space: the transition away from formula or breast milk at one year. There is a standard message. First, that your child should use formula through a year and then switch to milk. Second, that you should breastfeed for a year but that if you want to continue doing so after a year, that’s great.

The messaging invites two questions. First: why does formula use end at a year and breast milk does not? And second, why exactly a year?

To the first question: By a year, most kids are getting a lot of their nutrition through solid food sources, regardless of whether they were using formula or breast milk. This makes either of these less important as a food source. But since breastfeeding for an extended period is something people do for many reasons, there are reasons they might want to continue even as it becomes less important as a food source. In contrast, formula is only a food source, so there isn’t really any reason to continue using it past when its food value is higher.

To the second question: Nothing in medicine has a cutoff like this. There is no magical moment at 12 months when children switch from needing formula to needing cow’s milk. The most important nutrient difference at this time is iron — formula has more than cow’s milk, and for a kid who is consuming formula as a huge share of their calories, switching that all to milk before they are consuming much solid food could lead to iron deficiency. (Cow’s milk also has more protein and calcium, which is useful for a toddler.)

It sounds like this is not the situation you are in, if your child is eating three solid food meals a day. In this case, moving away from formula could make sense. This is an example of something you should discuss with your pediatrician before doing anything rash! There may be a desire to introduce some supplements, or target the diet, to make sure your child is getting their iron and other nutrient needs met.