A miracle mom has donated more than 600 gallons of her own breast milk to help hundreds of other parents feed their babies.

Selfless Elisabeth Anderson-Sierra, 29, devotes 10 hours a day to her “labor of love” and says it’s like a full-time job.

The mom of two has hyperlactation syndrome, which means she pumps around 1.75 gallons of breast milk a day — almost 10 times the 27-ounce average.

Her 6-month-old daughter, Sophia, consumes 20 ounces a day and the rest is handed over to local moms, gay couples and a milk bank for premature babies.

The precious liquid is packaged, labeled and stored in four huge freezers in the house where she lives with the girls and her husband, public safety officer David Sierra, 52.

Anderson-Sierra says she has fed “thousands” of babies with 78,000 ounces — more than 600 gallons — of breast milk since becoming pregnant with her eldest daughter, Isabella, 2½.

The former US Coast Guard boatswain’s mate, of Beaverton, Oregon, says producing the “liquid gold” is her “labor of love.”

She said: “I realized I was an overproducer when I was pregnant with my first child, but when I had my second baby, my supply ramped up. Now Sophia is 6 months old, I pump five times a day — as soon as I wake up, after breakfast, after lunch, after dinner and again at midnight.”

“I produce 70 to 80 ounces of milk during my first pump alone.”

“In total I will spend around five hours a day just pumping and then with storing, labeling, sterilizing, etc., I easily spend eight to 10 hours. Pumping is not fun — it is uncomfortable and it hurts — but it is my labor of love.”

“I’ve not had a day off in two-and-a-half years. It’s more than a full-time job. It is instant gratification when I donate locally because I see the babies and I see them thriving.”

“It will have helped thousands of children. The milk at the milk bank goes to micro preemies, so 1 ounce can feed three or four babies.”

“I don’t discriminate — I have donated to gay couples and to mothers who are on medication or had their breast removed due to breast cancer. It’s an amazing feeling.”

Anderson-Sierra usually breastfeeds at home but will also pump discreetly in restaurants, while driving and in other public spaces.

Around half of her milk is picked up from her house by local moms or couples who often choose to compensate her for her time.

The other half is donated to California milk bank Prolacta Bioscience.

Anderson-Sierra is paid $1 an ounce by the company to cover her time but does not profit.

She spends the money on the equipment, storage and extra food she needs to produce.

The devoted mom said: “Donating has been a massive part of my life for the past few years.”

“When I first started it was very, very hard, mostly because there is really no price on it and all the blood, sweat and tears that go into making it.”

“It was like giving away a portion of the paintings on the Sistine Chapel … priceless and hours of work.”

“There was also fear. What if I gave away all my milk and something happened to me to where I then dried up and couldn’t feed my own baby?

“I’d hear horror stories about that happening to mothers all the time! I’d then be the one in the position that I’d be desperate to find donor milk.”

“I eventually got over it and kept donating everything I had on hand. It makes me feel like I am giving back to my community and I’m participating in humanity.”

“I would encourage other moms to reach out to their own community and consider donating. Breast milk is like liquid gold — it should never be thrown away. And there is a high need for it out there.”