EXPLAINER: What's behind the baby formula shortage?

WASHINGTON (AP) — Many parents are hunting for infant formula after a combination of short- and long-term problems hit most of the biggest U.S. brands.

Millions of babies in the U.S. rely on formula, which is the only source of nutrition recommended for infants who aren't exclusively breastfed.

Here's a look at what's behind the problem and what parents can do:

WHY IS THERE A SHORTAGE?

Ongoing supply disruptions have combined with a recent safety recall to squeeze supplies.

The problems began last year as the COVID-19 pandemic led to disruptions in labor, transportation and raw materials — economy-wide issues that didn't spare the formula industry. Inventory was further squeezed by parents stockpiling during COVID-19 lockdowns.

Then in February, Abbott Nutrition recalled several major brands of powdered formula and shut down its Sturgis, Michigan, factory when federal officials began investigating four babies who suffered bacterial infections after consuming formula from the facility.

Abbott is one of only a handful of companies that produce the vast majority of the U.S. formula supply, so their recall wiped out a large segment of the market.

WHAT IS IN BABY FORMULA?

Most formulas are made from protein from cow's milk that's been altered to be easier to digest and enhanced with extra nutrients babies need for growth and development. The Food and Drug Administration sets specific nutritional requirements, including minimum amounts of protein, fat, calcium and a number of vitamins. Formula makers achieve these levels by adding various sugars, oils and minerals.

The formulas are designed to mimic breast milk, though studies have repeatedly shown better health for babies who are breastfed.

WHY CAN'T ALL MOTHERS RELY ON BREAST MILK?

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