According to Gram Research analysis, a 2026 cohort study of 723 Norwegian pregnant women found that lower vitamin A levels during pregnancy were associated with larger babies at birth. For every small decrease in maternal vitamin A (0.2 μmol/L), babies weighed 31 to 68 grams more, and nearly half of women had insufficient vitamin A by the third trimester. The findings suggest maintaining adequate vitamin A throughout pregnancy may help prevent excessive fetal growth.
A new study of 723 pregnant women in Norway found that mothers with lower vitamin A levels during pregnancy were more likely to have larger babies at birth. Researchers measured vitamin A in blood samples taken during the second and third trimesters and compared these levels to how much babies weighed when born. The findings suggest that vitamin A plays an important role in fetal development, and that getting enough of this nutrient during pregnancy might help prevent babies from being born too large. However, researchers caution that more studies are needed to confirm these results.
Key Statistics
A 2026 cohort study of 723 pregnant women in Norway found that vitamin A insufficiency increased from 8.6% in the second trimester to 43% in the third trimester, with 17.3% of babies born weighing 4,000 grams or more.
For every 0.2 μmol/L decrease in maternal serum retinol levels, babies weighed approximately 31 to 68 grams more at birth, according to the 2026 Norwegian cohort analysis of 723 pregnancies.
Mothers of larger babies (macrosomic infants) had significantly lower vitamin A levels in the third trimester and lower average levels across both trimesters compared to mothers of normal-weight babies in a 2026 study of 723 pregnancies.
The Quick Take
- What they studied: Whether the amount of vitamin A in a pregnant mother’s blood is connected to how much her baby weighs at birth
- Who participated: 723 pregnant women in Norway with healthy, low-risk pregnancies who had blood tests in their second trimester (around week 18-22) and third trimester (around week 32-36)
- Key finding: Mothers with lower vitamin A levels were more likely to have larger babies. For every small drop in vitamin A (0.2 units), babies weighed about 31 to 68 grams more at birth
- What it means for you: Getting enough vitamin A during pregnancy may help prevent babies from being born larger than ideal, which could reduce health risks for both mother and baby. Talk to your doctor about your vitamin A intake during pregnancy
The Research Details
This was a post-hoc analysis, which means researchers took data that had already been collected for another study and looked at it in a new way. They studied 723 pregnant women in Norway who were having healthy pregnancies with no major complications. Blood samples were taken twice—once in the middle of pregnancy (weeks 18-22) and again near the end (weeks 32-36). The researchers measured the exact amount of vitamin A in each blood sample using a special lab technique called high-performance liquid chromatography, which is very precise. They then looked at hospital records to find out how much each baby weighed when born and checked if there was a connection between the mother’s vitamin A levels and the baby’s birth weight.
This research approach is important because it follows women throughout their entire pregnancy, measuring vitamin A at two different times. This allows researchers to see how vitamin A levels change as pregnancy progresses and whether these changes matter for baby’s growth. By collecting real blood samples instead of just asking women what they ate, the study gets accurate measurements of actual vitamin A in the body. Looking at birth weight is meaningful because babies that are too large at birth can have health problems for both the baby and mother.
This study has some strengths: it measured vitamin A precisely using lab tests, included a fairly large group of women (723), and tracked them at two time points during pregnancy. However, there are important limitations to keep in mind. This was a post-hoc analysis, meaning the study wasn’t originally designed to answer this specific question, which can affect how reliable the findings are. The study only included women in Norway with healthy pregnancies, so results might not apply to all pregnant women worldwide. The researchers couldn’t prove that low vitamin A actually causes larger babies—they only found an association, meaning the two things happen together but one might not cause the other.
What the Results Show
The study found that vitamin A insufficiency (not quite deficiency, but lower than ideal levels) became much more common as pregnancy progressed. In the second trimester, about 8.6% of women had insufficient vitamin A, but by the third trimester, this jumped to 43%—meaning nearly half the women had lower-than-ideal levels. Interestingly, no women had severe vitamin A deficiency in the second trimester, but 1.9% developed it by the third trimester. About 17.3% of the babies born to these mothers were classified as macrosomic, which means they weighed 4,000 grams (about 8.8 pounds) or more at birth. Mothers whose babies were macrosomic had noticeably lower vitamin A levels in the third trimester and lower average levels across both trimesters compared to mothers of babies with normal birth weights. The key finding was that for every small decrease in vitamin A (0.2 μmol/L), babies weighed about 31 to 68 grams more at birth—roughly the weight of a few tablespoons of water.
The study also looked at how vitamin A levels changed between the second and third trimesters. Mothers of larger babies showed a bigger drop in vitamin A levels as pregnancy progressed. This suggests that maintaining adequate vitamin A throughout pregnancy, especially in the later months, may be important for preventing excessive fetal growth. The researchers noted that vitamin A insufficiency was surprisingly common in this high-income country where malnutrition is generally not a major problem, suggesting that even well-nourished populations may not be getting enough vitamin A during pregnancy.
This study adds to existing knowledge about vitamin A’s role in pregnancy. We already know that both too much and too little vitamin A can harm a developing baby, but most research has focused on severe deficiency in low-income countries. This study is notable because it examined the middle range of vitamin A levels in a wealthy country and found that even modest insufficiency may matter. The connection between maternal vitamin A and birth weight hasn’t been extensively studied before, so this research opens a new area of investigation. The findings align with what we know about vitamin A’s role in cell growth and development, suggesting that adequate vitamin A is needed for normal fetal growth patterns.
The researchers themselves emphasize that this study has important limitations. Because it was a post-hoc analysis (using data collected for a different purpose), the original study wasn’t designed to answer this specific question, which can affect reliability. The study only included women in Norway with healthy pregnancies, so we don’t know if these findings apply to pregnant women in other countries, different economic situations, or those with pregnancy complications. The study shows an association between low vitamin A and larger babies, but cannot prove that low vitamin A actually causes larger babies—other factors could explain the connection. Additionally, the study didn’t measure vitamin A intake from food or supplements, only the amount in the blood, so we don’t know if women were intentionally getting less vitamin A or if their bodies were processing it differently.
The Bottom Line
Based on this research, pregnant women should aim to maintain adequate vitamin A levels throughout pregnancy, particularly in the third trimester. Current recommendations suggest 770 micrograms of vitamin A daily for pregnant women. Good food sources include sweet potatoes, carrots, spinach, kale, and liver. However, it’s important not to take excessive vitamin A supplements during pregnancy, as too much can also be harmful. Talk with your healthcare provider about your vitamin A intake and whether you need supplementation. Confidence level: Moderate—this study suggests an association, but more research is needed to confirm causation.
This research is most relevant to pregnant women and those planning pregnancy, as well as healthcare providers advising pregnant patients. Women in high-income countries should pay attention because the study shows that vitamin A insufficiency can occur even in well-nourished populations. Women carrying multiple babies, those with certain medical conditions, or those taking medications that affect vitamin A should discuss this with their doctor. This research is less immediately relevant to non-pregnant individuals, though it highlights the importance of vitamin A for overall health.
If a pregnant woman improves her vitamin A intake, the effects on fetal growth would develop gradually over weeks to months. Birth weight is determined by growth throughout the entire pregnancy, so maintaining adequate vitamin A from early pregnancy onward is likely more important than making changes late in pregnancy. If you’re planning pregnancy, starting to ensure adequate vitamin A intake before conception is ideal.
Frequently Asked Questions
Does low vitamin A during pregnancy cause bigger babies?
Research shows an association between lower maternal vitamin A and larger birth weights, with each small decrease linked to 31-68 grams more weight. However, this study cannot prove vitamin A directly causes larger babies—other factors may be involved. More research is needed to confirm causation.
How much vitamin A do pregnant women need?
Pregnant women need 770 micrograms of vitamin A daily. Good sources include sweet potatoes, carrots, spinach, kale, and liver. Avoid excessive supplements, as too much vitamin A can harm fetal development. Discuss your intake with your healthcare provider.
What percentage of pregnant women have low vitamin A?
In this study of Norwegian women, vitamin A insufficiency affected 8.6% in the second trimester and 43% in the third trimester. This suggests that even in wealthy countries with good nutrition, many pregnant women may not get enough vitamin A, especially late in pregnancy.
Can I take vitamin A supplements during pregnancy?
Some vitamin A supplementation may be appropriate during pregnancy, but excessive amounts are harmful to fetal development. Work with your healthcare provider to determine safe supplementation based on your diet and blood levels. Never self-supplement without medical guidance.
Why does vitamin A matter for pregnancy?
Vitamin A is essential for fetal cell growth, immune system development, and normal growth patterns. Both deficiency and excess can cause problems. This research suggests that maintaining adequate levels throughout pregnancy, especially the third trimester, supports healthy fetal development and appropriate birth weight.
Want to Apply This Research?
- Log daily vitamin A intake from food sources (sweet potatoes, carrots, spinach, kale, liver, dairy products) and track weekly average intake against the 770 microgram daily target for pregnant women. Include supplement doses if applicable.
- Add one vitamin A-rich food to your daily meals: include a serving of orange or dark green vegetables at lunch or dinner, or add a small portion of liver once weekly. Use the app to set a reminder to include these foods and track completion.
- Track vitamin A sources weekly and monitor for consistency across all three trimesters of pregnancy. If using supplements, log the exact dose and timing. Share weekly vitamin A intake reports with your healthcare provider at prenatal visits to ensure you’re meeting recommendations without exceeding safe limits.
This research describes an association between maternal vitamin A levels and birth weight but does not establish that low vitamin A causes larger babies. Pregnant women should not change their vitamin A intake based solely on this study. All decisions about vitamin supplementation during pregnancy should be made in consultation with a qualified healthcare provider who understands your individual health situation. This article is for educational purposes and should not replace professional medical advice. If you are pregnant or planning pregnancy, discuss your nutritional needs with your doctor or a registered dietitian.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.