Quick answer
NIH and the US Preventive Services Task Force recommend a daily folic acid supplement for anyone planning or able to become pregnant. NIH's upper limit from supplements and fortified foods is 1,000 mcg a day. A Cochrane review of 5 trials in 7,391 women found no clear difference in miscarriages. Ask your doctor about your own amount.1,2,3
Key facts
- NIH says all women and teen girls who could become pregnant should get folic acid from supplements, fortified foods or both, because about half of US pregnancies are unplanned.1,2
- The upper limit for folate from supplements and fortified foods is 1,000 mcg a day for adults and 800 mcg for ages 14 to 18, including during pregnancy.1
- A Cochrane review of 5 trials with 7,391 women found no clear difference in miscarriages (risk ratio 1.10, range 0.94 to 1.28).3
- The label of a folic acid tablet says studies have not shown that folic acid increases the risk of fetal abnormalities, but cannot rule out harm.4
- NIH cites one study in which 1,000 mcg or more a day around conception went with lower development scores in children at age 4 to 5.1
What do NIH and the USPSTF say about folic acid in pregnancy?
NIH's fact sheets give the reason for the advice. Folate is needed to make DNA, demand rises in pregnancy, and the American College of Obstetricians and Gynecologists recommends a prenatal vitamin for most pregnant women so they get enough folic acid and other nutrients. The US Preventive Services Task Force recommends a daily folic acid supplement for everyone planning or able to become pregnant, starting at least a month before conception and continuing through the first 2 to 3 months of pregnancy.1
The advice reaches beyond people who are actively trying. NIH says about half of US pregnancies are unplanned, which is why the recommendation covers all women and teen girls who could become pregnant.1,2
About half of US pregnancies are unplanned, which is why folic acid advice covers everyone who could become pregnant.1
Is there an upper limit during pregnancy?
Yes. The limit is a ceiling for folic acid from supplements and fortified foods, not for the folate in ordinary food. NIH's table lists the same ceilings in pregnancy as outside it.1
| Age | Upper limit a day |
|---|---|
| 14 to 18 years | 800 mcg |
| 19 years and older | 1,000 mcg |
The upper limit for adults is 1,000 mcg a day of folate from supplements and fortified foods, which for folic acid equals about 1,667 mcg DFE. It is 800 mcg for teens aged 14 to 18. Folate naturally present in food has no limit, and the limits do not apply to higher doses taken under medical supervision.1,2
NIH adds that experts advise much higher amounts for women who have had a pregnancy affected by a neural tube defect. Those amounts go above the limit and are taken only under medical supervision.1
What did the Cochrane review find about safety?
The 2015 Cochrane review pooled 5 randomized trials with 7,391 women who took folic acid, alone or with other vitamins and minerals, around conception. Its main finding was fewer neural tube defects, with high-certainty evidence, which is the reason agencies recommend the supplement. It also looked at possible harms.3
| Outcome | What the review found | Certainty |
|---|---|---|
| Neural tube defects | Fewer with folic acid (risk ratio 0.31, range 0.17 to 0.58; 6,708 births) | High |
| Miscarriage | No clear difference (risk ratio 1.10, range 0.94 to 1.28; 7,391 pregnancies) | Moderate |
| Other birth defects | No clear difference (risk ratio 0.94, range 0.53 to 1.66) | Low |
| Cleft palate or cleft lip | No clear difference | Low |
The authors concluded that folic acid, alone or with vitamins and minerals, reduces neural tube defects but has no clear effect on other birth defects. Low-certainty results leave room for doubt, which is why the table shows ranges.3
What does a folic acid tablet label say about pregnancy?
A prescription folic acid tablet label is written for treating deficiency, but it addresses pregnancy directly. It says folic acid requirements are markedly increased in pregnancy, that studies in pregnant women have not shown an increased risk of fetal abnormalities, and that the possibility of fetal harm appears remote. It then adds that studies cannot rule out harm, so the tablet should be used during pregnancy only if clearly needed.4
In one study NIH cites, mothers who took 1,000 mcg or more of folic acid a day from supplements around conception had children with lower scores on several development tests at age 4 to 5 than mothers who took 400 to 999 mcg.1
What about methylfolate in pregnancy?
Some supplements contain methylfolate, also written 5-MTHF, instead of folic acid. NIH notes that it might suit some people with a gene variant called MTHFR C677T, and then says that the Centers for Disease Control and Prevention recommends folic acid, not 5-MTHF, for people who could become pregnant, even with that variant. The sources checked do not compare the safety of the two forms in pregnancy any further.1,2
Who should ask a doctor before taking folate in pregnancy?
Anyone who is pregnant or planning a pregnancy should ask a doctor or midwife which supplement and amount suit them. The sources point to these situations in particular.1
- A previous pregnancy affected by a neural tube defect, where much higher amounts are used under medical care.1
- An anti-seizure medicine such as phenytoin, carbamazepine or valproate, since folate can lower the medicine's blood levels and the medicine can lower folate.1,2
- Methotrexate or sulfasalazine, which both interact with folate.2
- A vitamin B12 deficiency or a diet with no animal foods, since large amounts of folic acid can hide low B12.2,5
- A prenatal vitamin together with fortified cereals and a separate folate pill, since the upper limit counts all of them together.1
Questions people ask
Is folic acid safe during pregnancy?
NIH and the USPSTF recommend folic acid for people who are or could become pregnant, and NIH's upper limit from supplements and fortified foods is 1,000 mcg a day for adults. A Cochrane review found no clear difference in miscarriages. Ask your doctor about your own amount.1,3
Is methyl folate safe during pregnancy?
NIH says the CDC recommends folic acid, not methylfolate, for people who could become pregnant, even with the MTHFR gene variant. The sources checked do not compare the two forms for pregnancy safety, so ask your doctor.1,2
Is folate safe in pregnancy at high doses?
NIH cites one study where 1,000 mcg or more a day around conception went with lower development scores in children at age 4 to 5, and says higher amounts are for medical supervision only. Ask your doctor before going above the upper limit.1
Is folic acid safe in pregnancy with iron or a prenatal vitamin?
NIH says folic acid is in multivitamins and prenatal vitamins, and the upper limit counts supplements and fortified foods together. The sources checked do not address any particular iron and folic acid product, so ask your doctor or pharmacist.1,2
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Sources
- National Institutes of Health, Office of Dietary Supplements. Folate: Fact Sheet for Health Professionals. Updated November 30, 2022. Opened 2026-10-07.
- National Institutes of Health, Office of Dietary Supplements. Folate: Fact Sheet for Consumers. Updated November 1, 2022. Opened 2026-10-07.
- De-Regil LM, Pena-Rosas JP, Fernandez-Gaxiola AC, Rayco-Solon P. Effects and safety of periconceptional oral folate supplementation for preventing birth defects (Cochrane systematic review and meta-analysis of 5 randomized trials). Cochrane Database Syst Rev. 2015;12:CD007950. Opened 2026-10-11.
- Folic acid tablets, 1 mg: prescribing information (Rising Pharma Holdings). DailyMed, U.S. National Library of Medicine. Published August 3, 2026. Opened 2026-10-07.
- National Institutes of Health, Office of Dietary Supplements. Vitamin B12: Fact Sheet for Health Professionals. Updated July 2, 2025. Opened 2026-10-07.
This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.