As the baby formula crisis worsens, it's also magnifying disparities in the U.S.

Shelves normally meant for baby formula sit nearly empty at a store in downtown Washington, D.C., on May 22. (Samuel Corum/AFP via Getty Images)

The mothers Tess Frear works with were already struggling. Most of them are single parents, typically from economically disadvantaged families. Sometimes they're escaping domestic violence; sometimes they're as young as 15.

For these new mothers, it was hard enough just trying to get basics such as diapers or clothing. Then came the baby formula shortage.