Vitamin D in pregnancy and your baby's brain: What a 10-year study found

Here is something quietly amazing about pregnancy nutrition. Some of what you prioritize today may still be showing up years from now, in ways researchers are only beginning to measure. A new study on vitamin D in pregnancy is a lovely example of exactly that. Scientists followed a group of children all the way to age 10, and what they found says a lot about how prenatal nutrition can play the long game.

Vitamin D often gets filed away as the bone nutrient. During pregnancy, it does far more than that. It behaves more like a hormone, influencing many systems in the body, and it's involved in processes that matter for your baby's developing brain. That raised a fascinating question for researchers: could a mother's vitamin D during pregnancy show up in her child's cognitive function a full decade later?

In a 2026 study published in JAMA Network Open, children whose mothers received a higher dose of vitamin D3 during pregnancy performed modestly better on tests of verbal and visual memory at age 10 than children whose mothers received a standard dose. Overall intelligence scores were similar. This was a secondary analysis, so it does not establish one ideal dose for everyone. It does suggest that vitamin D status during pregnancy may matter in ways that extend well beyond birth, which makes knowing your own level and talking with your provider worthwhile.

Key takeaways

• A 10-year follow-up linked higher-dose prenatal vitamin D with modestly better verbal and visual memory in children, though the differences were small and overall IQ was unchanged.
• The lesson is not that more is always better. it's that vitamin D status matters, and the right amount is personal.
• Knowing your 25(OH)D level and choosing a comprehensive prenatal, with your provider's guidance, is a practical next step.

What did the vitamin D and brain development study find?

To explore the question, researchers looked at 498 children whose mothers had taken part in a randomized vitamin D trial during pregnancy. From week 24 of pregnancy through one week after birth, the mothers received either 400 IU of vitamin D3 per day, a standard dose, or 2,800 IU per day, a higher dose.

Ten years later, the children completed a series of cognitive tests. On average, those whose mothers had received the higher dose performed modestly better on measures of verbal memory and visual memory. Overall intelligence scores looked about the same in both groups.

A few honest caveats matter here. This was a post hoc secondary analysis, not the trial's original question, and the differences were small. The study does not establish one perfect vitamin D dose or blood level for every pregnancy. What it does do is add to a growing conversation: prenatal nutrition may have ripple effects that reach well beyond pregnancy itself.

Why is vitamin D important during pregnancy?

Vitamin D supports several systems that are working hard during pregnancy, including immune function, bone health, and mood. It also plays a role in early brain development, which is part of why this new research is so interesting.

It helps to remember that vitamin D rarely works alone. Your baby's brain is built with the help of many nutrients working together, including choline and the omega-3 fatty acid DHA. If you want to go deeper on any single nutrient, our guides on vitamin D for fertility, pregnancy, and postpartum and choline during pregnancy are good next stops.

Because it's hard to get enough vitamin D from food and sunlight alone, especially in winter or for people with more melanin-rich skin, a well-formulated prenatal is often part of the picture.

Does this mean I should take more vitamin D?

Not necessarily, and this is the part worth slowing down for. The takeaway is not that more is always better. it's that your vitamin D status matters, and the right amount is genuinely personal.

Your needs can shift based on your starting level, your diet, your sun exposure, the season, your skin tone, and other factors. Rather than guessing, the most useful step is to ask your provider to check your 25(OH)D level, the standard blood marker for vitamin D, and to talk through whether your prenatal provides an amount that fits you. I frequently  find that intakes higher than the older 600 IU guideline may be needed to reach healthy levels, and our article on whether prenatal vitamins help fertility explores that nuance.

How much vitamin D is in WeNatal for Her?

WeNatal for Her provides 4,000 IU of vitamin D3, more than the older 600 IU general guideline and above the standard-dose arm in the study above. We formulated it with a higher amount because vitamin D supports immune function, bone health, and processes involved in your baby's development, and because many people find it hard to reach healthy levels from food and sunlight alone, particularly in winter or with more melanin-rich skin. Even so, the right amount is personal. Ask your provider to check your 25(OH)D level to see whether 4,000 IU is the right fit for you.

What should partners know?

Vitamin D matters for both parents. It plays a role in hormone health and overall wellbeing for men too, and preconception is a shared season, not a solo project. If your partner is preparing for pregnancy alongside you, WeNatal for Him offers vitamin D and other nutrients that support healthy sperm and whole-body health. 

When should you talk to your provider?

Vitamin D is powerful, and it's possible to have too much of it, so personalized guidance matters. Reach out to your healthcare provider if you:

• Are unsure how much vitamin D is right for you
• Would like your 25(OH)D level checked before adjusting your dose
• Take medication or have a medical condition that affects vitamin D
• Are planning a pregnancy and want to build a supplement routine that fits your needs

Frequently asked questions on vitamin D during pregnancy

Does vitamin D in pregnancy affect a baby's brain development?

Vitamin D is involved in early brain development, and a 2026 study found that children whose mothers took a higher dose during pregnancy performed modestly better on memory tests at age 10. The findings are promising but preliminary, and they do not prove that vitamin D alone determines cognitive outcomes.

How much vitamin D should I take during pregnancy?

There is no single right answer for everyone. The general recommendation has often been around 600 IU per day, but many providers find that higher intakes may be needed to reach healthy blood levels. The best approach is to have your 25(OH)D level checked and choose a dose with your provider.

What is a 25(OH)D test?

25(OH)D, or 25-hydroxyvitamin D, is the standard blood marker used to measure your vitamin D status. A simple blood test can tell you whether your level is low, adequate, or high, which helps you and your provider decide on the right amount for you.

Can you take too much vitamin D in pregnancy?

Yes. Vitamin D is fat-soluble, so very high intakes over time can build up and cause problems. This is exactly why testing your level and working with your provider is more helpful than simply taking more.

A note from WeNatal on pregnancy nutrition and long-term health

Pregnancy nutrition is about more than meeting today's needs. You are helping provide the nutritional building blocks for today's development, tomorrow's growth, and potentially health years down the road. That is what it means to build for life.

So know your vitamin D status, choose a comprehensive prenatal, and work with your provider to find what is right for you. Sometimes supporting your baby's future starts with something very small today.

Support your pregnancy with WeNatal for Her, and if your partner is preparing alongside you, explore WeNatal for Him. Not sure where to begin? Take our quick quiz to find the routine that fits your season.