Is folic acid before conception safe during pregnancy?

What does the evidence say about folic acid before conception during pregnancy?

1. Anyone who could become pregnant is advised to take 400 micrograms of folic acid a day, starting at least one month before pregnancy, which lowers the chance of neural tube defects such as spina bifida. 1
2. The neural tube closes on days 21 to 28 after conception, and the folate target is 400 micrograms of dietary folate equivalents a day outside pregnancy, rising to 600 during it. 2
3. A higher dose applies to some people: those who have had a previous child with a neural tube defect are advised to take 4 milligrams a day as a separate supplement, ten times the usual amount, starting at least three months before pregnancy and continuing for the first three months. 3
4. Folic acid absorbs better than the folate naturally present in food, at roughly 85 percent bioavailability when taken with food versus about 50 percent, and the tolerable upper intake level for synthetic folate is 1,000 micrograms a day for adults. 2
5. Some people are advised to take more than 1,000 micrograms a day, including those with a family history of neural tube defects, those on certain medications, and those with conditions that affect nutrient absorption. 1

Is folic acid before conception safe in each trimester?

• First trimester. The whole case for folic acid lives here. The neural tube finishes closing on days 21 to 28 after conception, roughly the point where a period is only just late. MotherToBaby advises 400 micrograms daily for anyone who could become pregnant, beginning at least a month ahead. ACOG frames the same window as one month before through the first 12 weeks.
• Second trimester. The urgency drops but the requirement does not. The pregnancy target is 600 micrograms of dietary folate equivalents a day, up from 400 outside pregnancy, and a standard prenatal covers that comfortably. There is no reason to add a second folate product on top unless your clinician asked you to.
• Third trimester. Stay on your prenatal and leave the dose alone. If you are on a high-dose regimen your provider prescribed, that is their call to review, not something to taper on your own. The tolerable upper intake level for synthetic folic acid from supplements and fortified foods is 1,000 micrograms a day for adults.