Why It's So Important to Have a Healthy Immune System During Your Pregnancy

Why It's So Important to Have a Healthy Immune System During Your Pregnancy

From the second the lines show up on the pregnancy test, your whole life changes, and you know that you would do anything in the world for your little one! So you read the books, revitalize your diet, hydrate like crazy, and generally do anything you can think of to make sure that your baby has the very best possible start in life. But one thing you might not have thought about at length is the inner world of your immune system.

You see, it's not only your growing abdomen, the volume of your blood, or the functioning of your breasts that changes during pregnancy; your immune system also undergoes some pretty significant shifts, starting within the gut (where a vast majority of the immune system resides).

As your immune cells become acquainted with your baby and your gut composition shifts to nurture and support your pregnancy, it can mean that your natural defenses are running a bit more sluggish on your behalf.

This “depressed” response in itself is an excellent reason to prioritize your immune health during pregnancy; however, when you consider that you essentially inherited your immune system from your mother, and that you’ll pass your immunity on to your child as well, it’s important to understand exactly how to support a balanced, healthy immune system during your pregnancy and beyond.

Where Does Your Immune System Come From?

We tend to think that the immune system is just something that develops naturally in the body, like your nervous system or your digestive system. And while that's partially true (you're born with an immune system, albeit an immature one), there's more to it than that. Babies start out life actually protected by something called maternal passive immunity, in which antibodies from the mom's body are passed through the placenta to the baby during the last three months of pregnancy.1

This type of immunity starts winding down in the first couple of weeks after the baby is born, but it's all right, because their own immune system really starts ramping up during this time as well––and a lot of it has to do with how much beneficial bacteria the baby is exposed to through the birth process, breast milk, and skin-to-skin contact.

Of course, exposure to bacteria at birth isn't the only thing that affects the immune system.

Like anything else in the body, the immune system and the gut microbiome (which plays a huge role in immunity) are always changing. Some factors continue to support the growth and diversity of the microbiome (and by extension the immune system) throughout our lives, including exposure to dirt and animals, eating probiotic and prebiotic foods, and exercising.

But there are also things that can have a negative impact on the gut and immune system, including many common things in our modern Western lifestyle, such as stress, eating lots of processed foods (especially those with sugar or gluten), exposure to antibiotics in food or as medication, our tendency to be slightly overzealous with cleaning products, and simply the process of aging—all of these can throw off the balance of beneficial and non-beneficial bacteria in the gut, which in turn affects the immune system.

Another Thing That Really Changes Your Microbiome? Pregnancy.

Like your immune system, your gut bacteria drastically change during pregnancy, especially the third trimester.2 While these changes are normal and healthy during pregnancy, they do mean that your immune system, which relies so heavily on your gut, can also be affected, which is why it’s important to put an emphasis on supporting your microbiome throughout your pregnancy.3

Research has shown that the healthier your immune system and gut microbiome are, the better it is for your baby's health. In fact, the microbes in your body affect your baby all throughout your pregnancy, birth, and the rest of their life.4

You see, as soon as you start to give birth, your baby's body begins to take in the bacteria from your vaginal canal, which then populates their gut microbiome and helps their immune system to grow stronger and recognize "friend from foe," so it will be able to respond properly and keep them healthy as they grow up.5

This is one reason that it's healthier for your baby to have a vaginal birth rather than a C-section, if possible. The exposure to bacteria during a vaginal birth is very different from that of a C-section, which may be why babies who are born via C-section are sometimes at risk for ongoing health conditions.6,7 This is also why it's so important for mothers and babies to have skin-to-skin contact as soon as possible after birth; the bacteria from the mother's skin is transferred to the baby and begins populating their microbiome.8 And the same goes for breastfeeding: the bacteria in your breast ducts is hugely beneficial to your baby, with lifelong effects on their immunity.9,10 And––you guessed it––the health of your breast microbiome is connected to that of the gut, as bacteria from your gut migrate to your breast ducts via the entero-mammary pathway.11 

So besides increasing your odds of staying healthy and feeling your best during your pregnancy, your immune system actually works to establish your baby’s immune system, which will protect them for the rest of their life!

Simple Ways to Support Your Immunity During Pregnancy

Now that you know just how beneficial a healthy immune system is for you and your little one, you're probably wondering what you can do to support it. The good news is, there are lots of really easy things you can do that can make a big difference in your immunity during your pregnancy––and you might already be doing more than you think.

1. Eat a diet that's high in prebiotics, and add a probiotic to your pregnancy supplements.

Since your immune system is so closely tied to your gut bacteria, the more you can do to boost your populations of beneficial bacteria, the better. One really simple, effective way to make sure your microbiome is happy is by eating prebiotic foods. Think of them like fertilizer for your microbiome; they contain the materials it needs to really take off.

You've got plenty of options, including things like oats, asparagus, bananas, apples, and kiwis, so you can easily work them in around pregnancy cravings. Or to make things much easier, you can take a prebiotic powder to really make sure you're getting the fuel your friendly flora need.

And while we're on the subject of supplements, consider adding a premium prenatal probiotic like PRO-Moms to the prenatal vitamins you're already taking. This can not only help populate your gut with beneficial bacteria, it can also help you get the most out of those prenatal vitamins by supporting the full absorption of nutrients, including the very-important folate.

2. Get outside as much as you can.

While you might be tempted to spend a little more time on the couch than normal during your pregnancy, do try to spend some time outside in nature. It's good for your mood, plus being out in the sun means that your body will naturally produce more vitamin D, which is connected with your immunity.

If you're up for it, try going for a walk or doing some other form of light exercise outside, too. Exercise is great for your immune system and your gut microbiome, and if you're doing it outside, you're exposing yourself to a lot of different kinds of bacteria, which can help diversify your microbiome.

3. Get enough sleep.

Getting enough sleep is always important, but it becomes especially key during pregnancy. This is not the time in your life to be burning the candle at both ends! Sleep is a key component in the health of your immune system, so make sure you're resting when you need to. If you're having trouble sleeping, there are lots of natural remedies to help soothe you or take care of the things that might be keeping you up, like an upset stomach. And if you haven’t yet begun taking a probiotic for your gut, this might change your mind––probiotics can also support healthy sleep.

4. Keep an extra eye on your oral hygiene.

This one might seem a little strange, but it makes sense if you think about how your mouth is connected to the rest of your body. Your mouth acts as the gatekeeper to your gastrointestinal tract, which, as you know, is where the majority of your immune system is found, so it's important to keep it as healthy as possible so it can do its job properly.

Plus, remember how your baby gets a little bit of bacteria via the placenta while you're pregnant? It turns out that some of those bacteria come from the mouth, so you've got one more reason to take care of those pearly whites.12

Ultimately, it's about tiny things that make huge changes––something you're about to get really familiar with as you build your new life with baby.

Life's about to change in a big way, so enjoy this special time, and remember, we're always here for you. From our #EmpoweredNursing campaign to PRO-Moms, our special probiotic formula designed specifically for expectant and nursing women, we love supporting mamas any way we can!


1. Palmeira, P., Quinello, C., Silveira-Lessa, A.L., Zago, C.A., Carneiro-Sampaio, M. (2012). IgG Placental Transfer in Healthy and Pathological Pregnancies. Clinical and Developmental Immunology 2012(2012), doi:10.1155/2012/985646

2. Koren, O., Goodrich, J.K., Cullender, T.C., Spor, A. . . . Ley, R. E. (2012). Host Remodeling of the Gut Microbiome and Metabolic Changes During Pregnancy. Cell 150(3). doi: 10.1016/j.cell.2012.07.008.

3. Nuriel-Ohayon, M., Neuman, H., and Koren, O. (2016). Microbial Changes during Pregnancy, Birth, and Infancy. Frontiers in Microbiology 7(1031). doi: 10.3389/fmicb.2016.01031.

4. Dominguez-Bello, M.G., Costello, E.K., Contreras, M. . . . Knight, R. (2010). Delivery Mode Shapes the Acquisition and Structure of the Initial Microbiota Across Multiple Body Habitats in Newborns. Proceedings of the National Academy of Sciences 107(26). doi: 10.1073/pnas.1002601107.

5. Hansen, C.H., Andersen, L.S., Krych L., Metzdorff, S.B. . . . Hansen, A.K. (2014). Mode of Delivery Shapes Gut Colonization Pattern and Modulates Regulatory Immunity in Mice. The Journal of Immunology 193(3). doi: 10.4049/jimmunol.1400085

6. Blustein, J., & Liu, J. (2015). Time to consider the risks of caesarean delivery for long term child health. BMJ, 350(Jun09 3) doi: 10.1136/bmj.h2410

7. Madan, J. C., Hoen, A. G., Lundgren, S. N., Farzan, S. F., Cottingham, K. L., Morrison, H. G., . . . Karagas, M. R. (2016). Association of Cesarean Delivery and Formula Supplementation With the Intestinal Microbiome of 6-Week-Old Infants. JAMA Pediatrics, 170(3), 212. doi: doi: 10.1001/jamapediatrics.2015.3732.

8. Mueller, N.T., Bakacs, E., Combellick, J., Grigoryan, Z., and Dominguez-Bello, M.G. (2015). The Infant Microbiome Development: Mom Matters. Trends in Molecular Medicine 21(2). doi: 10.1016/j.molmed.2014.12.002

9. Urbaniak, C., Burton, J. P., & Reid, G. (2012). Breast, Milk and Microbes: A Complex Relationship That Does Not End with Lactation. Women's Health, 8(4), 385-398.

10. Perez, P.F., Doré, J., Leclerc, M., Levenez, F., Benyacoub, J. . . . Donnet-Hughes, A. (2007). Bacterial Imprinting of the Neonatal Immune System: Lessons From Maternal Cells? Pediatrics 119(3).

11. Rodríguez J.M., The Origin of Human Milk Bacteria: Is There a Bacterial Entero-mammary Pathway During Late Pregnancy and Lactation? Advances in Nutrition 14;5(6). doi: 10.3945/an.114.007229

12. Aagaard, K., Ma, J., Antony, K. M., Ganu, R., Petrosino, J., & Versalovic, J. (2014). The Placenta Harbors a Unique Microbiome. Science Translational Medicine, 6(237).


Rachel Allen is a writer at Hyperbiotics who's absolutely obsessed with learning about how our bodies work. She's fascinated by the latest research on bacteria and the role they play in health, and loves to help others learn about how probiotics can help the body get back in balance. For more ideas on how you can benefit from the power of probiotics and live healthier days, be sure to subscribe to our newsletter. To learn more about how a healthy microbiome can enrich your life, subscribe to our newsletter.