A major review of 43 studies from 28 countries found that many pregnant women around the world don’t get enough iron, folate, and vitamin B12—nutrients their bodies need to stay healthy and support their growing babies. About 1 in 4 pregnant women lack iron, 1 in 9 lack folate, and 1 in 6 lack vitamin B12. Even more concerning, many women are missing multiple nutrients at the same time. These deficiencies can cause anemia (low red blood cells) and create health problems for both mothers and babies. The research shows this is a serious global health issue that needs better prevention and treatment programs.

The Quick Take

  • What they studied: How common are iron, folate, and vitamin B12 deficiencies in pregnant women around the world?
  • Who participated: Scientists reviewed 43 research studies involving pregnant women from 28 different countries across the globe to get a complete picture of the problem.
  • Key finding: About 28 out of 100 pregnant women lack iron, 11 out of 100 lack folate, and 17 out of 100 lack vitamin B12. Even more alarming, over half of pregnant women are missing at least two of these nutrients at the same time.
  • What it means for you: If you’re pregnant or planning to become pregnant, getting enough of these three nutrients is really important. Talk to your doctor about testing for these deficiencies and taking supplements if needed. This is especially important if you live in certain parts of the world where these deficiencies are more common.

The Research Details

Scientists looked for all published research studies about nutrient deficiencies in pregnant women from three major medical databases (PubMed, Embase, and Scopus) through August 2024. They found 43 studies from 28 countries that measured how many pregnant women were missing iron, folate, or vitamin B12. Two independent reviewers carefully checked each study to make sure the information was accurate and reliable.

They then combined all the data from these studies using a special statistical method that accounts for differences between studies. This approach allowed them to calculate overall percentages for how common these deficiencies are worldwide, rather than just looking at individual countries. The researchers also looked at combinations of deficiencies—cases where pregnant women were missing two or even all three nutrients at the same time.

This research approach is important because it gives us the big picture of a global health problem. Individual studies might show different results depending on where they were done and who they studied. By combining many studies together, scientists can see patterns that apply to pregnant women everywhere. This helps doctors and health organizations understand how serious the problem is and where to focus their efforts on prevention and treatment.

This is a systematic review and meta-analysis, which is one of the strongest types of research. The researchers used clear methods to find studies, had two people independently check the data to reduce errors, and combined results from 43 different studies. However, the studies included came from different countries with different healthcare systems, which means some variation in results is expected. The researchers were transparent about uncertainty in their findings by providing confidence intervals (ranges showing where the true number likely falls).

What the Results Show

The research found that nutrient deficiencies are extremely common in pregnant women worldwide. About 28% of pregnant women (roughly 1 in 4) don’t have enough iron, which is the most common deficiency. Folate deficiency affects about 11% of pregnant women (roughly 1 in 9), and vitamin B12 deficiency affects about 17% (roughly 1 in 6).

What’s particularly concerning is that many pregnant women are missing multiple nutrients at once. When researchers looked at combinations, they found that about 53% of pregnant women were deficient in iron or folate together, and about 50% were deficient in both iron and folate. This means that more than half of pregnant women in the world are missing at least two of these critical nutrients.

The study also found cases where pregnant women were deficient in all three nutrients simultaneously. About 36% had deficiencies in iron, 34% in folate, and 13% in vitamin B12 when looking at triple deficiencies. These combined deficiencies are especially dangerous because they work together to increase health risks.

The research revealed important patterns about how these deficiencies cluster together. Women who lack iron are very likely to also lack folate, suggesting they may have similar underlying causes like poor diet or limited access to nutritious food. The data also showed that deficiencies vary by region, though the study didn’t break down specific geographic patterns in detail. This suggests that local factors like food availability, healthcare access, and poverty levels play a role in how common these deficiencies are.

This comprehensive review confirms what smaller studies have suggested: micronutrient deficiencies in pregnancy are a widespread problem, not just a problem in poor countries. Previous research has shown these deficiencies are linked to serious complications like anemia, premature birth, and low birth weight babies. This new analysis provides updated global numbers and emphasizes that the problem is even bigger than previously thought, especially when looking at multiple deficiencies occurring together.

The study has some important limitations to understand. First, the 43 studies included came from only 28 countries, so some regions of the world may not be well-represented. Second, different studies used different methods to measure deficiencies, which can affect the results. Third, the researchers couldn’t always get complete information from every study, which added some uncertainty to their calculations. Finally, this review shows how common deficiencies are but doesn’t prove that supplements always prevent health problems—that would require different types of studies.

The Bottom Line

If you’re pregnant or planning to become pregnant, ask your doctor about being tested for iron, folate, and vitamin B12 deficiencies. Most doctors recommend prenatal vitamins containing these nutrients for all pregnant women, but testing can help determine if you need extra supplementation. Taking supplements as recommended by your healthcare provider is a safe and effective way to prevent these deficiencies. This recommendation has strong evidence supporting it.

All pregnant women should care about this research, but it’s especially important for women in developing countries, women with limited access to nutritious food, women who follow vegetarian or vegan diets (especially for B12), and women with digestive problems that affect nutrient absorption. Healthcare providers, public health officials, and policymakers should use this information to improve prenatal care programs and ensure pregnant women have access to affordable supplements.

If you start taking supplements now, your nutrient levels should improve within 4-8 weeks for iron and folate, though vitamin B12 may take a bit longer. The health benefits for your baby develop throughout pregnancy, so starting early is important. If you’re already pregnant, starting supplements immediately can still help prevent complications in the remaining months.

Want to Apply This Research?

  • Track your daily prenatal vitamin intake and any supplement doses. Log whether you took your iron, folate, and B12 supplements each day, and note any side effects like nausea or constipation that might affect compliance.
  • Set a daily reminder to take your prenatal vitamins at the same time each day (like with breakfast). If you experience side effects, log them in the app and discuss with your doctor about adjusting the timing or type of supplement.
  • Use the app to track your prenatal appointments and lab test dates for nutrient level checks. Record any symptoms of deficiency like fatigue, shortness of breath, or numbness. Share this data with your healthcare provider to monitor your progress and adjust supplementation if needed.

This research summary is for educational purposes only and should not replace professional medical advice. Pregnant women should consult with their healthcare provider before starting any new supplements or making dietary changes. If you have symptoms of nutrient deficiency like severe fatigue, shortness of breath, or numbness, seek immediate medical attention. The prevalence rates in this study represent global averages and may not apply to your specific situation. Your doctor can determine your individual risk and recommend appropriate testing and treatment based on your health history and location.