“Folic acid before conception and early in pregnancy reduces neural tube defects.”
Taking folic acid before and early in pregnancy cuts the risk of neural tube defects by about two-thirds.
If you could become pregnant, a daily folic acid supplement is a well-proven way to protect a future baby from neural tube defects. It works best when it is already part of your routine before pregnancy begins.
If you could become pregnant, start a daily supplement or multivitamin with 400 to 800 micrograms of folic acid now.
Talk to a healthcare professional if: you have had a pregnancy affected by a neural tube defect, you have a family history of these defects, or you take a medicine that interferes with folic acid, because you may need a different dose.
A Cochrane review of randomized trials rated the evidence high quality that folic acid prevents neural tube defects, and US guidance gives it the top grade. Timing matters because the critical period starts at least a month before conception.
Taking folic acid before and early in pregnancy cuts the risk of neural tube defects by about two-thirds. This benefit is specific to neural tube defects, not a promise to prevent every birth defect.
A Cochrane review of 5 trials with 7,391 women found folic acid, alone or with other vitamins, lowered the risk of neural tube defects (relative risk 0.31, from 6,708 births). It also lowered the chance of a repeat defect in women who had a previous affected pregnancy. Doses of 400 micrograms or more a day worked about the same. The trials did not show a clear effect on cleft lip or palate, heart defects or other birth defects. People with a common MTHFR gene variant can still process folic acid, and the CDC says the variant is not a reason to avoid it.
The US Preventive Services Task Force (2023, grade A) recommends that anyone planning or able to become pregnant take a daily supplement with 400 to 800 micrograms of folic acid. It advises starting at least 1 month before conception and continuing through the first 2 to 3 months of pregnancy. This advice does not cover people with a previous pregnancy affected by a neural tube defect, people at very high risk for other reasons such as family history, or people taking medicines that interfere with folic acid.
- De-Regil LM, Peña-Rosas JP, Fernández-Gaxiola AC, Rayco-Solon P. Effects and safety of periconceptional oral folate supplementation for preventing birth defects. Cochrane Database of Systematic Reviews. 2015;(12):CD007950. DOI: 10.1002/14651858.CD007950.pub3. PMID: 26662928. PMCID: PMC8783750
- US Preventive Services Task Force. Folic Acid Supplementation for the Prevention of Neural Tube Defects: Preventive Medication. Clinician Summary. Released August 1, 2023
- Centers for Disease Control and Prevention. MTHFR Gene Variant and Folic Acid Facts. Updated July 16, 2026