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

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.

"There's definitely desperation," said Frear, executive director of the baby supply bank Helping Mamas in Knoxville, Tenn. "These mamas are just scared, you know. What are they going to do?"

More than three months since...