Maternal Diet and Infant Immunity: A Strong Link

Pregnancy is such a magical time in a woman’s life. Instinctively, you know that you’re eating for two, and what you do matters a lot to your little new child. Your motivation is very high, as it should be, to do it right for your baby.

It’s not just about getting the right vitamins and the minerals and enough protein so the baby can grow healthy. Research shows that a mom’s diet shapes even the bacteria that’s going to be in her baby’s gut—what scientists call the microbiome—and even changes the makeup of her breast milk to help fight off infections in her baby.

This is really important because a healthy start for your infant begins before birth, and helps prevent sickness in those first crucial months of life. We’ll take a look at what we already know about mom’s diets and baby’s health, and then also look at a new study that adds in fascinating details of how this magic unfolds.

What We Already Know About Mom’s Diet and Baby’s Health

Pregnancy Diet

For many years now, doctors, scientists, midwives, and nurses have all stressed that what a woman eats during her pregnancy and while nursing her baby plays a huge role in her baby’s well-being after birth.

During the pregnancy, mom’s nutrition supplies everything that the baby gets. From their brain, their bones, all their organs, and so on, it all comes from what mom eats. If mom doesn’t eat it or have it in her own body, the baby doesn’t get it.

We know, for example, that folate is super important at the beginning of the pregnancy—before you even know you’re pregnant—for preventing birth defects like spina bifida. God has designed an amazing system of building babies during pregnancy.

Fetal Alcohol Syndrome

On the other hand, drinking alcohol causes lots of damage. Fetal Alcohol Syndrome (FAS) comes from drinking alcohol while pregnant. Symptoms include distinct facial features (small eyes, thin upper lip), growth delays, organ issues (heart), brain damage affecting learning/memory, and behavioral problems like hyperactivity and poor social skills. Avoiding alcohol during pregnancy is crucial.

So, what a mom does or doesn’t do sets the baby up for health or illness and weakness for his whole life. It is a lot of responsibility, but also a great opportunity as well.

And just because the baby is born doesn’t mean that he relies less on mom for his nutrition. Breast milk is still by far the best way to feed your baby all the way up through six months. 

Breast Milk is Best Milk

Breast milk is packed with antibodies, nutrients, and even good bacteria that helps set up the infant’s microbiome, which helps influence digestion, immunity, and even mood later in life. 

Studies have shown repeatedly that moms who eat a diet with lots of fruits, veggies, and whole grains pass on a diverse mix of these microbes (like bifidobacteria) both during birth and through breast milk. If mom eats junk food, it leads to a very undiverse and unhealthy microbiome in the baby, which can lead to more allergies, possibly even obesity, and frequent infections. Formula does not have the antibodies and beneficial bacteria found in even the unhealthiest mom’s breastmilk, so breast feeding is very important.

The immune factors in breast milk are very important for fighting infections because the antibodies in breast milk act as a shield, coating the GI tract to protect the mucosal lining from bad bacteria getting a foothold. This is why, when a mom with a nursing infant gets a cold, often her baby does not get sick because of the protection in the breast milk passed from mother to baby. On the other hand, when mom eats poorly, this shield is weakened and makes it easier for the baby to get colds and infections.

What’s New from This Latest Study?

A recent study was published in August 2025 in the journal E-Biomedicine. In this study, researchers took this knowledge a bit further. They examined the link between a mom’s diet and the baby’s immunity, evidenced by how often and how seriously her baby got sick. They also checked immune components like immunoglobulins in the breast milk and bacterial colonization in the infants.

There were two parts to the study:

Human Study: The research team observed real moms and babies from a group of women called the MAMI Birth Cohort. They gave moms a questionnaire to see what they ate during pregnancy. Then, they checked the baby’s gut bacteria. They checked breast milk for immunoglobulins and immune components. And they kept track of how often the infants got sick.

Animal Study: In the second part of the study, they did experiments with baby rats who were infected with a stomach virus, a rotavirus, while the mother rats were fed diets based on what the women ate. There were two kinds of diets for the mother rats: one that was higher in plant protein, fiber, fish oil, and then a diet that was higher in animal protein and lard.

What did they find? Moms that followed a more plant-rich diet had babies with fewer and milder infections. They found correlations between maternal intake of fiber, polyphenols, and carotenoids with better babies’ health and fewer infections. More infections were seen correlated with higher intake of cholesterol, n-3 alpha-linolenic acid (probably from canola and soybean oil, not flax or chia seeds or walnuts), total protein, and animal protein as well. (People eat so little vegetable protein that total protein is usually a proxy measure of animal protein intake.)

Fewer infections happened because the diet improved the baby’s microbiome—making it more diverse and helpful—and boosted the immune system. In the rat study, the pups from dams eating more plant protein and fiber and polyunsaturated fats showed a strong “Th1” immune response, which is great at fighting viruses.

This study confirmed what people had known previously about IgA, one of the antibodies in human breast milk. The study showed that IgA acted like a protector—indeed coating the baby’s gut to block out the bad germs.

In the rat study the researchers found that an antibody called IgG2c had this coating and protection role filled by IgA in humans. These immune components in milk worked hand in hand with the mom’s diet to shield their babies. The fiber and plant proteins that the mom ate seemed to encourage good bacteria to be passed through the breast milk that helped train the baby’s immune system. Additionally, a lower saturated fat intake lowered the mom’s inflammatory state and helped prevent inflammation from being passed along to the baby.

This new study builds on what we knew about microbiome links to health outcomes in infants already. Here’s an article looking at moms and infants in Guatemala, but the data is really dense and it doesn’t tease out the connection between real foods and outcomes. It’s stuck with just nutrient correlations to outcomes. This new study makes the connections much clearer.

Why Does This Matter for Moms and Babies?

This is good news for moms who want to take care of their babies. You really can make a difference in your baby’s outcomes. It’s not just by chance that babies get infections. If you eat more salads, beans, oats, nuts, and so on (things with fiber and plant protein in them), it could mean fewer infections for your baby after they’re born. 

The message is clear. Pregnancy and breastfeeding are an excellent opportunity to give your baby a healthy boost that lasts a lifetime. 

This research also reminds us that God has created a very intricate and robust way to connect your health as a mom to your baby’s health. So we can always praise God for the amazing systems that He has created in us, even as we marvel at His wisdom and understanding.