What is the recommended daily intake of folic acid for pregnant women?

Folic Acid Supplementation for Pregnant Women

All pregnant women should take 400-800 μg (0.4-0.8 mg) of folic acid daily, starting at least one month before conception and continuing through the first trimester. 1, 2

Standard Dosing Recommendations

• The American College of Medical Genetics and Genomics (ACMG) recommends a daily folic acid intake of 400 μg (0.4 mg) for all women of childbearing age 3
• The US Preventive Services Task Force (USPSTF) recommends that all women who are planning or capable of pregnancy take a daily supplement containing 400-800 μg (0.4-0.8 mg) of folic acid 2
• Folic acid supplementation should begin at least 4 weeks prior to planned conception and continue through at least the first trimester 3
• This supplementation is advised in addition to consumption of folic acid-fortified food 3
• After 12 weeks of gestation, continuation of 400 μg folic acid supplementation is recommended throughout the remainder of pregnancy 1

High-Risk Population Dosing

• Women at high risk for neural tube defects require a higher dose of 4,000 μg (4 mg) daily 3, 4
• High-risk criteria include:
  • Personal, family, or prior pregnancy history of neural tube defects 3
  • Type 1 diabetes mellitus 3
  • Exposure to high-risk medications during early pregnancy (e.g., valproic acid, carbamazepine) 3, 1
• This higher dose should begin at least 12 weeks prior to conception 3
• After completion of 12 weeks gestation, high-risk women can reduce to the standard dose of 400 μg (0.4 mg) 3

Safety Considerations

• The upper limit for folic acid supplementation is established at 1,000 μg (1 mg) per day for most women 3, 5
• Exceeding this limit may potentially mask vitamin B12 deficiency 3
• Higher doses should only be used under physician supervision 3
• Folic acid is water-soluble and rapidly excreted, so cumulative effects are unlikely 3

Effectiveness and Public Health Impact

• Daily intake of 400 μg of folic acid before conception can reduce the risk of neural tube defects by approximately 80% 6
• Despite food fortification efforts, dietary folic acid alone is likely inadequate for maximal protection against neural tube defects 4
• Even with adequate supplementation, not all cases of neural tube defects can be prevented due to their multifactorial etiology 3, 1

Common Pitfalls to Avoid

• Waiting until pregnancy is confirmed to start supplementation - neural tube closure occurs within the first 28 days after conception, often before pregnancy recognition 3
• Relying solely on dietary sources - food folates are about half as bioavailable as synthetic folic acid 3
• Discontinuing supplementation too early - continuation through at least the first trimester is recommended 1
• Failing to identify high-risk women who need higher doses 3
• Not considering that approximately 50% of pregnancies are unplanned, supporting the recommendation for all women of childbearing age to take folic acid supplements 1