A formula brand set up a phone line for parents to share their feelings about the shortage. Now it's taking the messages to Congress to push for change.

• Parents who use formula are voicing their frustrations to Congress about the nationwide shortage.
• Hundreds have shared their stories on a "vent line" set up by Bobbie, a formula startup.

The strain of exclusively pumping breast milk was taking such a toll on Vanessa Wisniewiski, a first-time mom, that she began to develop symptoms of postnatal depression.

"It was all-consuming and causing a very bad situation mentally for me to continue," Wisniewiski, 35, of Sacramento, California, told Insider, adding, "I told myself, 'I can't do this by myself anymore.'"

Days after deciding to move her 4-month-old, Silas, to formula, she was shocked to learn about the nationwide shortage.

The crisis is the result of supply-chain issues and a recall after the Food and Drug Administration investigated reports of bacterial infections in babies. The nationwide out of stock rate was at 43% for the week of May 10, according to Datasembly.

Wisniewiski said she had no choice but to continue pumping "around the clock" and hope that lactation supplements would help boost her dwindling supply of breast milk.

Out of anger and frustration, she joined the Hungry for Change campaign launched by Bobbie, an infant-formula startup, demanding that lawmakers step in and solve the problem.

Wisniewiski left a tearful voicemail on the company's "vent line," saying that "people should be able to feed their babies" and that "there needs to be fucking contingency plans." The recording was delivered to Congress on Thursday with messages from other incensed parents.

Outraged parents have rallied to make politicians address the infant-formula crisis

Laura Modi, Bobbie's CEO and cofounder, also wrote a letter to lawmakers on Capitol Hill. Modi, a mom of three, told Insider that politicians must listen to "regular moms and dads" affected by the shortage.

"Lived experience really matters," Modi said, adding that "the US House of Representatives is 73% male and the average age is 58."

She added: "They're not feeling viscerally what is happening, and if they're not hearing directly from those who are going through it, we're not going to see change."

Jessyca O'Brien, who has a 1-year-old daughter named Luna, expressed her outrage on the vent line too.

"I think Congress and everybody else just needs to get their shit together and focus on what's important," she said in the recording.

She accused policymakers of being "so focused" on the rights of unborn children while "not taking care of those babies after they're born."

"It's absurd, and I've cried so many tears," Wisniewiski told Insider. "I wouldn't wish the way I've been stressing on any new parent."

Parents say representatives have sent them generic responses

O'Brien, 29, from Farmingdale, Maine, told Insider she'd been unable to buy enough of the specific formula that Luna needs for her lactose intolerance.

She said that she'd tried giving the baby whole milk and some regular formula she managed to find but that Luna would vomit them up.

"It's really distressing because a lot of women, myself included, have done everything we can to breastfeed," O'Brien said, adding that Luna had been unable to latch onto her nipples from birth.

She added: "I don't have the option to breastfeed, and if you use formula, at the moment, you can't feed your child."

She said she's now relying on donations from members of a Facebook support group for moms in the same position. She described the need for parents to depend on each other for help as "ridiculous."

"I've written to our local lawmakers and reached out by phone and email," O'Brien said. "But all I get back is a generic letter."

She added: "You feel like they're representing you, but not listening to you."

Wisniewiski said she believes that the people in power can no longer ignore the problem.

"This is food, this is nutrition and something that can't be overlooked because it doesn't affect you," she told Insider. She concluded: "This is life or death for babies."