Extreme breast milk donor has been pumping 4 years straight

This breast-feeding Portland mom has only two kids of her own, but she’s breaking records for feeding hundreds more.

Along with her two daughters, Isabella, 4 and Sophia, 2, Elisabeth Anderson-Sierra estimates she’s fed about 250 other babies with her breast milk, which she donates or sells at one dollar per ounce via a Facebook page, a common platform for the breast-milk black market.

The 31-year-old claims she’s an unofficial world-record holder for the number of ounces donated: In 2018, the official Guinness World Record was 53,081 ounces, but Anderson-Sierra tells The Post that to date she’s donated about 200,000.

Anderson-Sierra has hyperlactation syndrome, which causes her to produce 230 ounces of milk per day. That’s about eight times more than the average pumping mother, says Dr. Linda Dahl, a Midtown-based breast-feeding expert and ENT, who consults many over-producers in her practice. “It’s like they don’t have an off-switch,” Dahl says. “It’s a combination of hormones, and I bet most of her breast is made of glandular (milk-producing) tissue.”

The sale and private donation of breast milk is largely unregulated, but Anderson-Sierra could be held liable if her donations cause any harm or sickness.

Plus, hyperlactation comes with its own health risks. Says Dahl, “The dangers of oversupply are mastitis, which can develop in hours,” but adds that breast-feeders have shared their fruits throughout history. “There are some women who produce so much milk that they can literally feed a village.”

Though milk banks for over-producers exist, the lengthy screening process and pasteurization makes the final product expensive. Anderson-Sierra says that she’s seen costs of up to $10 an ounce, while she charges just a dollar per ounce.

“I’m not out to [make a profit]. People think that I make bank, but really it just helps sustain what I do,” Anderson-Sierra tells The Post, adding that the price she charges for her product accounts “for time and supplies.”

Anderson-Sierra, who keeps frozen bricks of breast milk in industrial-size freezers in her garage, connects with clients through social media. Kathy Yao, a mother of triplets who welcomed her babies through a surrogate, is grateful for Anderson-Sierra’s milk. “It’s been a huge, huge saver for us,” Yao tells The Post. “My girls consume about 80 or 90 ounces a day, and if you try to go to a milk bank, it’s like five or six bucks an ounce. You just couldn’t sustain that.”

But not all her customers are parents with babies in need.

“You see fetish inquiries . . . I get it daily,” says the over-producer, who adds, “I’ve sold to bodybuilders,” (the iron pumpers swear by its muscle-building properties). Despite the cringeworthy requests, and rigorous pumping schedule of six sessions every day, Anderson-Sierra also has dealt with thieves after her stash — “we put cameras in. I call it ‘operational security,’ ” — but insists it’s worth it in the end.

“It will always be rewarding to help others in this capacity,” says the milk martyr. “It saves lives.”