Your Baby's Maturing Immune System

baby lying on rug eating pacifier


Until your baby can crawl, they are basically fully in your control. Once they start to crawl, they want to move all the time, and the gig is up.

Somewhere between 6 and 9 months, babies take off. They might roll, crawl, pull-up, and cruise, but they start using their arms and legs to get where they want to be. 

Once your baby is ready to be apart from you, it is also their chance to take-over the job of immune regulation and microbiome building.

Kicking up Dust

As your baby moves, especially across floors and carpets, they kick up dust, dirt, pollen, and anything else that’s been tracked into your house into their mouths and lungs. Research showed that the particular way they half drag their bodies across the floor pulls 4 times the dust adults experience deep into their lungs. 

As with all things bacteria, this can be both a good thing or a bad thing. If you live in a place with high lead levels, it is incredibly important to keep shoes out of your house and your floors clean, as your baby can get high lead exposure. On the plus side, as your baby plays inside they will start to rapidly increase the number and variety of bacteria in their lungs. This has been shown to lower their risk of developing asthma. 

Mouthing Toys

One of the grosser parts of having a baby in the house is that suddenly everything is suspiciously wet. Babies use their mouths to learn about the objects around them. They get used to different textures, which will make them comfortable with a variety of foods.  It’s also how they develop muscles to be able to chew and talk. 

While the drool everywhere can be gross, babies pick up bacteria from their siblings, pets, and family members from these objects. Once babies have the coordination to put things in their mouths, they are likely doing more to expand their bacteria exposure than mom or dad is. 

As they perform the experiments over and over of “what makes me sick,” their immune system is paying attention and learning. This time of immune learning is why many doctors think the crawling phase (~6-10months) is so critical for regular exposure to eggs, nuts, fish, etc.   

Choosing Foods

Some babies are picky from the start about flavors, textures, smells, and consistency. Others don’t care what you feed them as long as you give them more. Although you still pick and make your baby’s meals, your baby will invariably decide what they actually eat. 

Your job is to make sure that they get to try as many foods as possible, that they have some of whatever you are eating, and that they are getting enough of the eggs and nuts that will protect them from food allergies. This is easier than it sounds if you try Bird Feeding or throw almost anything into a blender. 

For the trickier foods, like nuts, that don’t always blend small enough, 2 scoops of Lil Mixins Infant Powders 2 times a week is all you need.