Understanding the Latest Findings
Recent research from Australian universities suggests that high folic acid exposure during pregnancy—driven by fortified foods and high-dose supplements—may be associated with a higher risk of gestational diabetes (GDM). The study compared 1,100 women who conceived before folic acid food fortification (introduced in 2009) with 1,300 women who conceived after fortification, finding a notable rise in GDM diagnoses in the latter group. The post-fortification cohort showed 15% gestational diabetes, compared with 5% in the pre-fortification group.
The researchers also reported higher levels of certain biomarkers in the post-fortification group, including serum folate, red cell folate, prolactin, human placental lactogen, and placental growth hormone. Red cell folate levels above the normal range increased dramatically, from 0.5% pre-fortification to 57.6% post-fortification. Those with red cell folate excess had about 48% more GDM cases, suggesting a potential link between excessive folate exposure and glucose intolerance during pregnancy.
What this Means for Expectant Mothers
Dr. Tanja Jankovic-Karasolos, lead author from the Robinson Research Institute, cautions that while folic acid remains essential for preventing neural tube defects, there needs to be careful balance in a fortified food environment. “The challenge is to maintain protection against neural tube defects while avoiding excess exposure,” she said. The findings align with a broader concern: higher maternal folate levels could influence placental function and hormone secretion in ways that raise GDM risk.
According to the researchers, supplementation should still be guided by evidence-based practices rather than a blanket reduction. They emphasize the standard preventive dose of 400–500 micrograms of folic acid in the periconception period and during the first trimester, unless a clinician indicates otherwise. The risk of duplication is real; taking multiple supplements that contain folic acid beyond this window can lead to unnecessary excess.
Guidance for Clinicians and Public Health Policy
Clinicians are urged to review individual supplement intake and consider the broader fortified diet context when advising patients. Dr. Jankovic-Karasolos suggests the potential value of folate status checks for women with high or unclear exposure and to intensify gestational diabetes screening and lifestyle counseling for those with high folic acid intake. Higher-dose folate (800 micrograms to 5 milligrams) may be warranted in special circumstances, such as prior neural tube defect pregnancies or certain medical conditions, but this should be carefully weighed against potential metabolic risks.
The study’s authors call for a review of supplementation guidelines in light of rising GDM rates observed in Australia—from 5.4% in 2011 to 19.3% in 2022. They acknowledge that factors like maternal age, obesity, ethnicity, and diagnostic criteria contribute to risk, but suggest that folate excess may be an overlooked driver. They also note that many women in fortification environments exceed the commonly cited 1,000 microgram daily limit, underscoring the need for nuanced guidance rather than blanket restrictions.
Practical Takeaways for Expectant Families
For many pregnant people, the safest path is the “right dose, right window” approach. Before pregnancy and in the early weeks of gestation, prioritize supplements only when indicated by a clinician. Avoid doubling up with multivitamins fortified with folic acid, and stay aligned with guideline-based recommendations. In fortified settings, ongoing evaluation of folate exposure and robust gestational diabetes screening may help balance neural tube protection with metabolic health.
Ultimately, the research highlights an important shift: as populations move from deficiency to potential excess in folate exposure, public health guidance must evolve to preserve benefits while mitigating risks. Ongoing dialogue among researchers, clinicians, and policymakers will shape future recommendations around folate status, supplementation timing, and diabetes screening during pregnancy.
