Baby’s Journey from Sterile to Germs

By Heidi Lam, B.So.Sci(Hon), IBCLC

We are living in a world full of microorganism like bacteria, virus and fungi. Even varies part of the human body have bacteria, like the skin, gut, and mucosal membranes.  They are needed for a normal life.  When we look closely into the immunology of breast milk, we will be amazed how Mother Nature intends to protect our offsprings to sustain a world full of bacteria.

 Born Naturally from Sterile to Germs

Baby lives in a sterile environment inside the mother’s womb, well nourished, protected and germs free. Suddenly, one day, the baby is born right next to mother’s anus, where you will expect plenty of bacteria.

Then the baby is put on to the mother’s body for skin-to-skin contact.  He touches and licks the mother’s skin, contacting bacteria there.

So what would happen to all those germs?

These are actually normal bacteria that will colonized the baby’s skin, gut and varies mucosal membranes, namely microflora.  The microflora will prevent the growth of dangerous bacteria by competing them for nutrients and space.

In the baby’s gut, the normal bacteria flora will compose of more “good” bacteria like Bifidobacteria and Lactobacilli, and less “bad” ones such as E. coli and Staphylococcus aureus.

However, babies are born very immature comparing to other mammals.  All their body systems are still developing.  The epithelium lining of infant’s gut is not yet intact, meaning germs and antigens may get through the “holes” of the “leaky gut” and goes into the blood stream and body tissues.

If that happens, a war will rise between the bacteria and the baby’s still immature immune system! The baby will defense his body against the “invader” and starts a series of reaction, namely infection.  This will cause inflammation, tissue damage, clinical symptoms and high energy cost.

To put it plainly, the baby gets sick.

He needs to use a lot of his energy to fight the war, and normal growth and development is compromised.

Breast Milk Defenses

This sounds a bit scary. So let’s go back to the newborn at the mother’s chest after birth.

He moves and searches and touches his mother’s nipple by his tiny hand.  After some efforts his mouth finds the nipple!  He latches on easily and gets colostrum in reward.

As you can see now, having contact with all the germs right after birth, the baby has a far greater need for immunological protection than for nutrition in the early days.

Mother nature is well aware of this too! The quantity of colostrum is low, but it has a high concentration of a major protein component called SlgA antibodies.

SlgA antibodies in breast milk are specific to mother’s bacteria in the gut. Can you see now how lucky that baby is born next to mother’s anus, so that he gets the same bacteria of his mother, which the SlgA antibodies are targeting to.

One important function of SlgA is to protect against the “bad” bacteria that colonized the newborn’s gut.  SlgA antibodies will bind the specific microorganism, so that they cannot attach to baby’s mucosal membrane, thus avoiding infection.  SlgA also support the development of baby’s own immune system.

 Varies components works together

Other breast milk protein components also work together with SlgA to protect the baby.  Lactoferrin kills bacteria, virus and fungi, while Lysozyme, working with Lactoferrin and SlgA will attack E. coli.

Moreover, carbohydrates call oligosaccharides will act as food for the “good” bacteria and enhance the growth of bifidobacteria and lactoobacilli.  More “good” bacteria in the gut means less space and food the “bad” pathogenic bacteria to grow.  Oligosaccharides will also catch and sweep the bacteria from the intestine and urinary tract and get excreted.

Now, what a good news to the baby’s still mature immune system.  Mother’s breast milk defenses.  Breast milk get rids of the enemies before they can go into the blood stream and tissue.  Infection is avoided and the baby does not need to react with inflammation, tissue damage, clinical symptoms, nor to lose energy.  War is relieved!

 Importance of normal gut bacteria

This first contact of mother’s bacteria, together with the defense of breast milk, is a good education for the baby’s immune system. The normal bacterial colonization in baby’s gut significantly stimulates the growth of his immune system.  It learns how to defend the baby from infection. It also learns not to react to normal substance such as food or pollen, which may otherwise induce allergic reactions.

These lessons are learned in a safe and energy saving way.  Now the baby can use his energy for optimal growth and development.

What a happy and healthy breast-fed baby mother nature has intended!

 Risk when against the nature

Now lets consider another scenario.

Baby was born via cesarean section.  He did not contact mother’s gut flora near the anus. He was then separated with mother for hospital procedures while mother being sewed up.  The baby was handled by varies hospital staffs, other than his mother and father.  He came in contact with the bacteria of other people’s skin and hospital environment.

After two hours, baby was brought to the mother to nurse. However, the most alert timing for the baby after birth is passed, and he seemed to be very sleepy.  He latched briefly and went to sleep.  Mother was in pain and baby was kept in the nursery.  Every 3-4 hours the nurse would bring the baby to the mother but breastfeeding did not go smoothly.  After trying for a few times, the baby started formula.

Since baby did not develop the normal gut and skin flora as his mother did, he had a different bacterial colonization.   He also contacted germs of other people, which he may not have those specific SlgA antibodies from colostrum to fight for.  With early start of artificial feeding, he do not have the supply of necessary SlgA and other factors to promote a growth of “good” bacteria in the gut, nor to help killing and blocking out pathogenic bacteria.  Since his immune system was still immature, when some bacteria was able to attach to the mucosa in the gut or urinary tract, so unfortunately, infection occured.

The baby then had to fight a war between his immature immune system and the germs. He had inflammation, tissue damage, energy loss and clinical symptoms.

He was then prescribed antibiotic.  However antibiotic treatment has a strong effect on the gut microflora.  It promotes the growth of some “bad” bacteria like Klebsiella and Enterobacter, risking for more serious illness. Antibiotic may also suppress the growth of some “good” bacteria, risking the colonization of disease causing bacteria.

Furthermore, cows milk protein is a common allergen.  It may, leak through the immature “leaky gut” and goes into the blood stream, which then cause a series of allergic reaction.

This tragic condition does sound very familar!  How many times we see baby get sick early on and having allergic reactions?

By looking into the different scenarios, we can see breastfeeding is a natural way to protect our babies and allow him to have a normal and healthy growth and development.

Starts skin-to-skin contact with baby after birth and goes on to breastfeeding is the key!



Hanson Lars A., Immunobiology of Human Milk: How Breastfeeding Protects Babies, 2004, Sweden, Pharmasoft Publishing.

(updated: Nov 2011)

© Copyright 2011 Lam Yan Yee Heidi.  All rights reserved. No reprint or upload in any format and in any media without permission. Enquiries or reprint permission contact Heidi. Email: Tel:(852) 9301 6381


2 Comments (+add yours?)

  1. Dakota Gramza
    Mar 01, 2012 @ 06:57:55

    I believe this site contains some real great information for everyone : D.


  2. Amy
    Mar 02, 2012 @ 10:40:17

    Like the blog


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