From the Guidelines
Recommended Daily Intake of Folic Acid
The recommended daily intake of folic acid during the first trimester of pregnancy is 400 to 800 mcg.
- This recommendation is based on evidence from several studies, including a large randomized, controlled trial that demonstrated a statistically significant reduction in incidence of neural tube defects in women who took a multivitamin with 0.8 mg (800 μg) of folic acid in the periconceptional period 1.
- The USPSTF recommends that all women planning or capable of pregnancy take a daily supplement containing 0.4 to 0.8 mg (400 to 800 μg) of folic acid to reduce the risk for neural tube defects (Grade A recommendation) 1.
- This recommendation is supported by other studies, including a cohort study that found a protective effect of folic acid against neural tube defects in women who took multivitamins containing 0.8 mg (800 μg) of folic acid 1 month before planned conception 1.
- Additionally, the American College of Obstetricians and Gynecologists and other organizations recommend that women capable of becoming pregnant take 400 mcg (0.4 mg) of folic acid daily to reduce the risk of neural tube defects 1.
From the Research
Recommended Daily Intake of Folic Acid
The recommended daily intake of folic acid during the first trimester of pregnancy is:
- 400 micrograms (mcg) per day for all women capable of becoming pregnant to prevent neural tube defects (NTDs) 2
- 4000 micrograms (mcg) per day for women who have previously had an NTD-affected pregnancy, beginning at least 1 month before conception and continuing through the first trimester 2
Importance of Folic Acid Supplementation
Folic acid supplementation is crucial for preventing neural tube defects, with studies showing that periconceptional folic acid supplementation can prevent 50% or more of NTDs 2
- The timing of folic acid supplement usage is critical, as the neural tube closes by Day 28 post-conception 3
- Women who start folic acid supplementation before conception have a lower risk of NTDs compared to those who start after conception 3
Effects of Continued Folic Acid Supplementation
Continued folic acid supplementation after the first trimester of pregnancy may have additional benefits, including:
- Lower homocysteine concentrations in the third trimester 4
- Increased maternal and cord blood folate status 5
- Potential reduction in pregnancy complications associated with hyperhomocysteinemia 4 However, one study found that continued folic acid supplementation with 400 micrograms/day in the second and third trimesters of pregnancy significantly increased the risk of large-for-gestational-age (LGA) births 6