Is folic acid safe during pregnancy?

What does the evidence say about folic acid during pregnancy?

1. 600 mcg DFE a day is the recommended dietary allowance for folate, and it is the same across every pregnancy age band. 1
2. The upper limit is 1,000 mcg a day for ages 19 and up and 800 mcg for ages 14 to 18, and it applies only to synthetic folate from supplements and fortified foods. No upper limit was set for folate from food, because high intakes from food have not been reported to cause harm. 1
3. 400 mcg of folic acid a day is advised before conception and 600 to 800 mcg during pregnancy, and starting at least one month ahead lowers the chance of neural tube defects. 2
4. Some people are advised to take more than 1,000 mcg a day, including those with a family history of a pregnancy affected by a neural tube defect. That is a decision made with a clinician, not at the pharmacy shelf. 2
5. About 35.8 percent of pregnant women in the United States get less folate from food than the estimated average requirement, while 33.4 percent of those aged 20 to 40 go over the upper limit for supplemental folate. Both ends of that range are common. 3

Is folic acid safe in each trimester?

• First trimester. This is the trimester folate is really about. The neural tube closes in the first few weeks, often before anyone knows they are pregnant, which is why the advice starts a month before conception rather than at your first appointment.
• Second trimester. The 600 mcg DFE target holds steady. Most prenatal vitamins carry 600 to 800 mcg of folic acid, so a daily prenatal almost certainly covers you without a second supplement on top.
• Third trimester. The number does not change. If you are stacking a prenatal with a B-complex or a fortified drink mix, add up the synthetic folic acid, because about a third of pregnant adults already clear the 1,000 mcg ceiling.