I have a world record for donating breast milk that's the equivalent of 800 2-liter bottles of Coke. I will eventually have a double mastectomy to stop.

• Elisabeth Anderson-Sierra has a rare medical condition called hyperlactation syndrome.
• The mom produces so much breast milk she pumps for five hours a day and donates it to preemies.

This as-told-to essay is based on a conversation with Elisabeth Anderson-Sierra. It has been edited for length and clarity.

My A-negative blood type is rare and in demand. Before I got pregnant with my older daughter, Isabella, in 2014, it made sense for me to donate blood as often as I could. I liked the fact that I was helping people.

Now, more than eight years on, I donate my breast milk to preemies and other newborns who need the nutrition to survive. So far, I have donated at least 1,600 liters of milk to babies across the US. I recently set the Guinness World Record for the largest donation of breast milk by an individual. It was fun, but I hope it raises awareness about milk donation.

I have a condition called hyperlactation syndrome, and I produce up to 200 ounces of milk a day and feed about 40 ounces of that to my 7-month-old son, Benjamin. The diagnosis in 2014 finally explained why I'd been lactating since I was 14 weeks pregnant. By the time I was 20 weeks pregnant, I was producing about 30 ounces a day. I'd put washcloths under my shirt to soak it up.

Things got so uncomfortable that I got a hand pump and then an electric one. Producing milk was actually more uncomfortable than being pregnant. I went on to make even more milk after my daughter Isabella was born.

It was important for me to nurse her, but I didn't know how difficult it would be to maintain a nursing relationship with my baby with such a massive amount of milk to manage. I'd have to pump before breastfeeding. If I tried to nurse her when I was full, she would essentially get waterboarded. I needed to pump so often that I was pretty much housebound. Life as a new mom is already isolating, but it felt even worse for me.

I wanted to help others who were struggling to give their babies breast milk

I was diagnosed with hyperlactation when Isabella was 3 months old. I had a bunch of tests, including a CAT scan of my pituitary gland, which was enlarged. The doctors checked to see if I had a pituitary tumor that was causing too much prolactin — thank goodness it wasn't that. They said that during my pregnancy, the hormonal shift led to the enlargement of the pituitary gland. It's normal for a pregnant woman to have a slightly enlarged gland after giving birth, but it usually returns to its normal size. But mine was abnormally enlarged and had stayed that way.

The endocrinologist said that I could take the medication bromocriptine to reduce my prolactin supply. But if I did, I could potentially lose all of my supply and not have enough milk to feed Isabella. The other option was close monitoring, medical care, and testing to make sure that I stayed healthy. I went for the second option because I wouldn't consider the idea of being unable to nurse my baby.

I got the idea to donate my milk to a local midwives' practice even before I had my daughter. You can't donate blood when you're pregnant, and I wanted to help other mamas who'd given birth and were struggling to give their babies breast milk.

Then I started to donate it to a large milk bank based in California. I also gave it to local moms who contacted me on Facebook. A lot of babies in my home city of Portland, Oregon, have ended up with my breast milk.

In the beginning, the refrigerator in the kitchen was packed with frozen milk that was ready for donation. My husband, David, had to remove the ice maker. Then we bought two chest freezers to put in the garage. It doesn't take long for them to reach capacity, even though I'm donating so many of the pouches.

I got pregnant with my second daughter, Sophia, two years after Isabella was born. I needed to pump before I nursed her, just like I'd done with her sister. It's the same with Benjamin. It's funny because all my kids were tiny when they were born. Then around the 4-month mark, they became super chunky because they fed so much.

I'm considering a double mastectomy in the future so I no longer lactate

Meanwhile, my older children still like drinking my milk in their oatmeal. They don't get sick from childhood illnesses like colds and viral bugs from school, and I believe my milk has helped with their immune system.

Over the years, advances in technology have given me a lot more freedom. I can pump while I'm out and about. I pump while I drive, using a portable breast pump made by BabyBuddha. I've got it down to five or six sessions a day. I've discreetly pumped during outdoor concerts surrounded by people, and nobody noticed.

Still, I'm considering having a double mastectomy because I feel like I've exhausted the other medical routes. It's hard to wrap my head around, though. If I do have the surgery, it will be a while after I've stopped nursing Benjamin. In the meantime, I'll keep donating my milk.

People have said I'm an angel because I've helped so many babies survive. Even though I broke the world record for milk donation, it's hard for me to sit with that praise and attention. But nice words add to the positive side of this medical condition. They fill my cup.

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