Breastfeeding is good for babies, there’s no question about it.

However, you may be surprised to learn that certain properties in breast milk can change from feeding to feeding in response to a baby’s needs.

Mallory Smothers brought attention to this change when she posted a photo of her breast milk and wrote about it on Facebook.

The Arkansas mom wrote that her baby girl had been “congested, irritable, and sneezing,” and probably had a cold.

The next time Smothers pumped, she noticed a distinct change in the appearance of her breast milk.

It was thicker and darker than the milk she had pumped earlier. In fact, it resembled colostrum, the “liquid gold” produced in the early days of breastfeeding.

“The human body never ceases to amaze me,” she wrote.

She is not alone in her amazement. To date, the post has been shared more than 75,000 times.

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What’s so Special About “Liquid Gold”?

Colostrum is thick, has a golden color, and serves a valuable purpose. It provides just the right nourishment to get a newborn off to a healthy start.

According to La Leche League International, colostrum is produced during pregnancy and for a few days after childbirth. It is high in carbohydrates and protein but low in fat, and it has a higher concentration of antibodies than mature milk.

Colostrum is easy for a newborn to digest and it has a mild laxative effect. These things make it easier to pass early stools (meconium), which helps to prevent jaundice.

Colostrum also has high concentrations of leukocytes (white blood cells) to help destroy bacteria and viruses that cause disease.

Mothers continue to make colostrum for several days after childbirth before mature milk starts to come in. And if breastfeeding is continued the milk will change as your baby’s needs change.

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Adapting to a Baby’s Needs

“There are many physiologic responses that take place between mother and infant that result in changes in some of the cells in breast milk,” said Nancy Hurst, Ph.D., RN, IBCLC.

“Hormonal, immune factors, nutritional components...truly an amazing process,” Hurst, the director of women's support services at Texas Children's Pavilion for Women, told Healthline.

Leigh Anne O'Connor, IBCLC, a private practice lactation consultant in New York City, explained that when babies nurse, their saliva gets into the milk ducts.

“The milk responds to this feedback and makes milk that is designed for the specific baby,” O’Connor told Healthline. “If the baby or mom or other family members are sick, there will be antibodies created to make a ‘vaccine’ to protect the baby by shortening the duration of the illness or flat out preventing it.”

Changes in breast milk may even reflect the time of day. According to O’Connor, it contains more melatonin at night, which helps the baby sleep better.

In humid weather breast milk may contain more water to hydrate the baby. And as the baby grows, the nutrients in breast milk become more concentrated.

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What Moms Need to Know

There is still a lot that we are learning about breast milk,” said Hurst. “The greatest benefit comes from exclusive breast milk feeding during the first six months of life.”

Hurst also explained, “With regard to making milk, moms need to know how important it is to breastfeed exclusively during the early days of breastfeeding to ensure they build their milk volume adequately.”

According to O’Connor, even if you don’t breast feed exclusively, a baby who gets some breast milk will have a stronger immune system than a baby who gets none.

“Moms need to know that there is so much noise out there, and information,” said O’Connor. She also recommends that mothers should trust their intuition and that the IBCLC (International Board Certified Lactation Consultant) is a resource if help with breastfeeding is needed.