Researchers combined results from 10 studies to understand how folate (a B vitamin) in early pregnancy relates to blood sugar levels later in pregnancy. They found that pregnant women with higher folate levels tended to have slightly higher blood sugar readings during a standard glucose test at 24-28 weeks of pregnancy. However, the increases were small, and scientists caution that more research is needed to fully understand what this means for pregnant women and their babies. This finding is surprising because folate is important for fetal development, so doctors need to figure out the best folate levels for both mother and baby.

The Quick Take

  • What they studied: Whether the amount of folate (a B vitamin) a pregnant woman has in her blood during the first 16 weeks of pregnancy is connected to her blood sugar levels later in pregnancy (around 24-28 weeks).
  • Who participated: The analysis combined data from 10 different research studies that looked at pregnant women and measured their folate levels early in pregnancy and their blood sugar levels later in pregnancy.
  • Key finding: Pregnant women with higher folate levels had slightly higher blood sugar readings during a glucose tolerance test (a standard test doctors use to check for gestational diabetes). For every increase in folate, fasting blood sugar went up by 0.01 mmol/L, 1-hour glucose went up by 0.17 mmol/L, and 2-hour glucose went up by 0.10 mmol/L.
  • What it means for you: If you’re pregnant or planning to become pregnant, this suggests that more folate might be associated with higher blood sugar levels. However, the increases are small, and doctors still recommend folate for pregnancy health. Talk to your healthcare provider about the right folate amount for your individual situation rather than making changes on your own.

The Research Details

This is a meta-analysis, which means researchers looked at 10 existing studies and combined their results to find patterns. They searched medical databases through June 2025 for studies that measured folate levels in pregnant women during the first 16 weeks of pregnancy and then measured their blood sugar levels during a glucose tolerance test (a drink test doctors use) at 24-28 weeks of pregnancy.

The researchers used a standardized method to combine the results from all 10 studies, which helps them see the overall pattern across different research groups. They also looked at whether results were similar when they focused on studies from different time periods or with different types of participants. They rated the quality of each study using a standard scoring system called the Newcastle-Ottawa Scale to make sure they were combining reliable information.

A meta-analysis is valuable because it combines information from multiple studies, which gives a more complete picture than any single study could provide. By pooling results from 10 different research groups, scientists can see whether a pattern holds up across different populations and research methods. This approach helps identify real relationships while accounting for the fact that individual studies might have different results due to chance or differences in how they were conducted.

The researchers found substantial variation between studies (high heterogeneity), which means not all studies showed exactly the same results. This variation suggests that factors like different populations, study methods, or how folate was measured might have affected the findings. The researchers were transparent about these limitations and recommended caution when interpreting the results. The small number of studies (10) also means the findings should be considered preliminary rather than definitive. The confidence intervals (the ranges showing uncertainty) were very narrow for some measurements but wider for others, indicating varying levels of certainty across different findings.

What the Results Show

The main finding was that higher folate levels in early pregnancy were associated with higher blood sugar levels measured later in pregnancy during the glucose tolerance test. Specifically, for every standard increase in folate levels, fasting blood sugar (measured before eating) increased by 0.01 mmol/L, blood sugar measured 1 hour after drinking glucose increased by 0.17 mmol/L, and blood sugar measured 2 hours after drinking glucose increased by 0.10 mmol/L.

These increases are small in absolute terms. To put this in perspective, normal fasting blood sugar is typically below 5.1 mmol/L, and these associations represent tiny fractions of that normal range. The 1-hour and 2-hour glucose increases are more noticeable but still modest.

The researchers also looked at whether the pattern held true when they examined folate levels measured in the middle of pregnancy (around 16-20 weeks) rather than very early pregnancy. They found similar associations, suggesting the relationship between folate and blood sugar might persist throughout pregnancy.

When researchers divided studies into groups based on different characteristics, they found that the positive association between folate and blood sugar levels appeared consistently across different subgroups. This consistency suggests the finding is not limited to one particular type of study or population. However, there was substantial variation between studies (more than 70% variation), meaning some studies showed stronger associations than others. This variation suggests that factors not examined in this analysis—such as differences in how folate was measured, the populations studied, or other health factors—might influence the relationship.

Previous research had suggested that very high folate levels might increase the risk of gestational diabetes (a type of diabetes that develops during pregnancy), but the specific relationship with different blood sugar measurements hadn’t been thoroughly examined. This meta-analysis provides more detailed information about how folate relates to different glucose measurements. The findings align with the previous concern about high folate and glucose metabolism, but the actual increases in blood sugar are quite small. This research adds nuance to the conversation about folate supplementation in pregnancy by showing that the relationship is more complex than previously thought.

The researchers identified several important limitations. First, only 10 studies were included, which is a relatively small number for a meta-analysis. Second, there was substantial variation between studies (high heterogeneity), making it harder to draw firm conclusions. Third, the studies used different methods to measure folate and glucose, which could affect how results compare. Fourth, the analysis couldn’t determine whether the association between folate and blood sugar is actually causal (meaning folate causes higher blood sugar) or just a correlation (they happen together but one doesn’t necessarily cause the other). Finally, the researchers couldn’t examine whether these small increases in blood sugar actually affect pregnancy outcomes or baby health, which is what really matters clinically.

The Bottom Line

Based on this research, there is no recommendation to reduce folate intake during pregnancy. Folate remains essential for preventing birth defects and supporting fetal development. The increases in blood sugar associated with higher folate are very small. Current medical guidelines recommend adequate folate for all pregnant women. If you’re pregnant and concerned about blood sugar levels, discuss your individual folate and glucose management with your healthcare provider rather than making changes based on this research alone. The confidence level for these findings is moderate—the pattern appears consistent across studies, but more research is needed before making clinical changes.

This research is most relevant to pregnant women, women planning pregnancy, and their healthcare providers. It’s particularly important for women who are concerned about gestational diabetes or who have risk factors for high blood sugar during pregnancy. Healthcare providers may use this information when counseling pregnant women about folate supplementation, especially those with blood sugar concerns. However, this research should not discourage anyone from taking recommended folate supplements, as the benefits for fetal development are well-established. Women without blood sugar concerns don’t need to change their folate intake based on this study.

If folate does affect blood sugar, the effect appears to develop gradually throughout pregnancy, as the association was seen both in early pregnancy and mid-pregnancy folate levels. Blood sugar changes would likely be measurable within weeks of changes in folate levels, but the actual health impact of these small increases is unknown. Any changes to folate intake should be discussed with a healthcare provider and monitored through regular glucose testing during pregnancy.

Want to Apply This Research?

  • Track folate intake (from supplements and food sources like leafy greens, legumes, and fortified grains) alongside blood glucose readings from your glucose tolerance test or home monitoring. Record the date, folate source, estimated amount, and corresponding glucose readings to identify any personal patterns.
  • If you’re pregnant and concerned about blood sugar, work with your healthcare provider to establish a target folate intake that balances the need for adequate folate with blood sugar management. Use the app to log folate-rich foods and monitor how different folate sources (supplements vs. food) might affect your individual glucose levels.
  • Maintain a pregnancy nutrition log that tracks folate intake, blood glucose readings from routine tests, and any symptoms of high blood sugar (increased thirst, frequent urination). Share this log with your healthcare provider at prenatal visits to identify any concerning patterns specific to your pregnancy and adjust recommendations accordingly.

This research summary is for educational purposes only and should not replace professional medical advice. Folate is an essential nutrient during pregnancy, and current medical guidelines recommend adequate folate intake to prevent birth defects. The small associations found in this study between folate and blood sugar levels do not mean you should reduce folate intake without consulting your healthcare provider. If you are pregnant or planning pregnancy, discuss your individual folate needs and blood sugar management with your obstetrician or midwife. Do not make changes to supplements or diet based on this research alone. This meta-analysis has limitations and represents preliminary findings that require further research before clinical recommendations change.