Why food matters during pregnancy

Food supplies the building blocks of your baby's brain, and your gut talks to your brain through nerves, hormones, immune signals, and the microbiome.

Illustration of a pregnant woman looking down at her belly, with a glowing brain and a baby with a glowing brain inside

How nutrition supports your baby's brain and nervous system

1

Building the brain's structure

Nutrients from food help form brain cells, the protective myelin coating around nerves, and the chemical messengers that shape mood, attention, and learning.

  • Protein
  • Omega-3 fats
  • Iron
  • Choline
  • B vitamins, including folate
  • Zinc
  • Iodine

2

Supporting a healthy stress-response system

Balanced, nourishing meals help keep blood sugar steady and may lower inflammation. Together with sleep, movement, and support, this creates a calmer internal environment for both of you while your baby's own stress system is forming.

3

Shaping the gut microbiome

Your gut bacteria change during pregnancy and influence immune development, metabolism, and signals that may reach the developing brain. A varied, fiber-rich diet supports a more diverse microbiome. Much of this research is still early, especially in humans.

What this means for your baby

Nutrition in pregnancy supports brain growth and connections, emotional regulation, the setting of the stress response, and long-term physical and mental health. It doesn't mean perfection is required; consistent nourishment builds a supportive foundation.

Gentle reassurance for parents

Food is one piece of development, not the whole story. Cravings, nausea, stressful weeks, or imperfect days don't cause harm. Bodies and brains are resilient, and overall patterns matter far more than single meals.

What we suggest

  • Eat regular, balanced meals when you can
  • Include protein, fruits, vegetables, healthy fats, and whole foods
  • Stay hydrated
  • Take a prenatal vitamin as directed
  • Avoid alcohol and other substances your provider advises against
  • Talk with your provider or midwife about supplements and any dietary needs

The gut–brain connection, in plain words

Gut–brain axis diagram: nerve pathways, hormones, immune signals, and the gut microbiome linking a pregnant parent and baby

Your gut and brain are in constant conversation through the vagus nerve, hormones, immune signals, and gut bacteria. Researchers call this the microbiota–gut–brain axis. In pregnancy, your gut–brain system reaches your baby indirectly, through the placenta: hormones, immune signals, and nutrients and other substances made with help from your gut bacteria. The vagus nerve links each person's own gut and brain; it doesn't connect parent to baby directly.

Illustration of a woman eating a colorful plate of brain-healthy foods

Variety helps most: vegetables, fruits, beans, whole grains, eggs, fish low in mercury, nuts, and fermented foods if you enjoy them. Your provider can tell you which fish and cheeses to avoid.

Foods to handle with care

A few foods carry a higher risk of infections or mercury that can harm a developing baby.

Raw or undercooked

Meat, poultry, eggs, and seafood, including sushi with raw fish. Cook until hot all the way through.

Unpasteurized

Raw milk and cheeses or juices that aren't pasteurized. Check the label.

High-mercury fish

Shark, swordfish, king mackerel, marlin, orange roughy, bigeye tuna, and tilefish from the Gulf of Mexico. Lower-mercury fish like salmon, sardines, and shrimp are good choices.

Deli meats and hot dogs

Heat until steaming before eating to lower the risk of listeria.

Your provider can tailor this to your health, culture, and food traditions.

What the science says, and what it doesn't yet

A review in the journal Gut Microbes gathered research on how the trillions of bacteria living in our gut may shape brain development before and after birth. Much of this work comes from studies in mice, so treat it as a promising window into how development might work rather than settled advice.

A two-way conversation

Gut bacteria can signal the brain through the vagus nerve, hormones, the immune system, and substances they make. The brain talks back too: in animal studies, stress changed the gut lining and which bacteria thrived.

Fiber feeds the conversation

Gut bacteria break down fiber from plant foods into short-chain fatty acids, which help keep the gut healthy and may affect the brain. They also make vitamins, including K2 and B12, which matters for the developing nervous system.

Before birth

The placenta protects and feeds the growing brain. In mice, it even turns the mother's tryptophan (an amino acid from protein foods) into serotonin for the developing forebrain. Animal studies also suggest the mother's gut bacteria during pregnancy can influence how offspring handle stress.

After birth

A baby's gut starts gathering bacteria at birth, during the same window when the brain is growing fastest. How a baby is born and fed both shape those early bacteria. In mice, early life looked like a sensitive window: bacteria added later didn't undo the early differences.

Four ways gut bacteria talk to the brain

A 2022 review in Clinical and Experimental Pediatrics pulls together what researchers know about how the gut and brain communicate. Most of the evidence comes from lab animals, so read this as how the system may work, not as a to-do list.

1

Messenger chemicals

Gut bacteria can make versions of the brain's own chemical messengers, including GABA (a calming signal), serotonin, and dopamine. These act on the body or change how it makes its own.

2

Immune signals

When the gut is out of balance or an infection is fighting, the immune system releases inflammatory messengers called cytokines. These can reach the developing brain and change how brain cells grow.

3

The vagus nerve

About 80% of the vagus nerve's fibers carry information up from the body to the brain, including news about the gut. In animal studies, a calming effect from a probiotic disappeared when the vagus nerve was cut.

4

Bacterial by-products

Most of the body's serotonin outside the brain (about 90% in humans) is made in the gut, and bacterial by-products influence how much. Butyrate, a short-chain fatty acid made from fiber, helped strengthen the blood–brain barrier in mice.

How gut bacteria help build a brain

The brain's own immune cells

Microglia, the brain's immune cells, help shape connections between nerve cells, build their insulation, and clear away what isn't needed. In mice raised without gut bacteria, or given antibiotics, microglia stayed immature. Putting bacteria back, or adding short-chain fatty acids, helped them recover.

Learning, memory, and connections

Mice without gut bacteria showed differences in the hippocampus (a learning and memory area), in the insulation around nerves in the prefrontal cortex, and in genes for building synapses. Some of these changes reversed when normal bacteria returned. Early life appears to be an especially important window.

Mice aren't babies. These studies show that the gut can influence brain development. They don't tell us what to eat, or promise outcomes for your baby.

What shapes your gut bacteria

Many things change which bacteria live in your gut. Researchers list these as the main ones, and they are also why gut studies are so hard to compare.

  • Diet
  • Medicines, including antibiotics
  • Stress
  • Age
  • How a baby is born
  • Your genes and other body factors
Most of these aren't things to fix or feel guilty about. Take medicines your provider prescribes, eat what you can, rest when you can, and ask for support when stress piles up. Calm and care help your whole body, gut included.

Infections in pregnancy

Why infections matter for the brain

A strong immune reaction to an infection during pregnancy can affect how a baby's brain develops. Research has linked flu in the first trimester with a higher chance of schizophrenia in the child later in life. The chance for any one family remains low, and most babies whose mothers had infections are not affected.

What you can do

  • Wash your hands often
  • Get the vaccines your provider recommends
  • Handle food safely (see "Foods to handle with care" above)
  • Call your provider early if you have a fever or feel unwell

Gut bacteria and autism: what we know, and what we don't

No single "autism bacterium"

Several reviews pooled 9 to 18 studies each. They found different patterns, and a bacterium that was lower in one review was sometimes higher in another. Studies used different methods, and diet and medicines can also change gut bacteria. Researchers can't yet name a bacterial pattern that explains autism.

Treatments are still experimental

Probiotic trials have mixed results: some saw gains in certain behaviors and others saw none. Small studies of fecal microbiota transfer, a medical procedure, reported improvements that lasted at two years, but they were small and had no placebo group. It is not an approved treatment for autism.

What this means for you

Autism isn't caused by parenting, by what you ate, or by how your baby was born or fed. Before you start probiotics, special diets, or supplements for autism, talk with your child's doctor.

Source: Kim, G.-H., & Shim, J.-O. (2022). Gut microbiota affects brain development and behavior. Clinical and Experimental Pediatrics, 66(7), 274–280.

Myth or fact?

Tap each card to check it.

However your baby is born or fed, they can thrive. Research on birth method and feeding describes averages across many babies, not your baby's future. A cesarean that keeps you safe and formula that keeps your baby fed are good care.
Next: how eating in pregnancy and feeding children affect mental health. Food, feeding, and mental health
Gentle reassurance: nausea, cravings, and imperfect days are normal. What matters is the overall pattern, and prenatal vitamins help fill gaps. If eating feels very hard, tell your provider.

You don't have to wait until it's bad

These free US lines are for parents, partners, and anyone supporting them, during pregnancy and after.

Outside the US, contact your local emergency number or health service. If someone has confusion, hallucinations, or thoughts of harming themselves or the baby, call 911 or go to an emergency room.

Physical warning signs like chest pain, trouble breathing, a severe headache, or heavy bleeding during pregnancy or in the year after birth also need care right away. See urgent warning signs

Safety information in other languages: Español · Français · 中文 · Tiếng Việt · Italiano