Generally speaking, infants are fed formula only during their first year. So at any given time, the number of infants of "formula age" equals the total number of babies born in the previous twelve months. Here's what that looks like:
The number of live births had been trending downward for years and then dropped more sharply at the beginning of the pandemic. As a result, during the first half of 2021 the number of infants aged 0-12 months plateaued at a record low of 3.57 million.
But in the second half of 2021, that number increased sharply to 3.66 million, an increase of 90,000, and has probably increased another 50,000 since then. According to the CDC, approximately half of these babies are fed formula rather than being breastfed.
This prompts a bit of speculation: Lots of US corporations seem to have decided in 2020 to cut back on production but then never made plans for the pandemic to end and demand to go back up. In the case of infant formula companies, that mistaken inclination would have been reinforced by the fact that the US birth rate had been steadily declining for years even before the pandemic.
The middle of 2021 is about when the infant formula crisis began. Why? Manufacturers blithely wave off questions by blaming it on labor shortages, supply chain issues, packaging problems, and instability caused by the Ukraine war. These are the standard excuses offered by every company suffering from shortages and nobody ever questions them. After all, everyone knows about the pandemic labor shortages and the supply chain issues and all that. So it sounds plausible.
And maybe it is. But another possibility is that infant formula manufacturers made the same mistake so many other companies did: they cut back production and assumed demand would never return. This might have remained a modest mistake causing only a few temporary shortages here and there while production was eventually ramped back up, but then in February the Abbott recall turned a modest mistake into a catastrophe. I wonder if this is what really happened?