Q
When should I start folic acid for pregnancy?
⚡ Quick answer
3 months before trying to conceive. Continue through first trimester at minimum.
Folic acid (vitamin B9) is the single most important nutrient before conception. Start at least 3 months before trying to conceive — earlier is better.
Why: folic acid prevents neural tube defects (spina bifida, anencephaly). The neural tube forms in weeks 3-4 of pregnancy — often before women know they are pregnant. Levels must already be optimal at conception.
Dose:
- General population: 400mcg (0.4mg) daily
- Higher risk (history of NTD, diabetes, epilepsy meds): 4-5mg daily under medical guidance
- BMI over 30: 5mg daily often recommended
Which form:
- Folate (methylfolate, 5-MTHF): natural form, better for those with MTHFR gene variants (30% of population)
- Folic acid: synthetic form, what most prenatals contain
Food sources:
- Leafy greens (spinach, kale, romaine)
- Asparagus
- Lentils and beans
- Avocado
- Citrus fruits
- Beetroot
- Eggs
- Liver (highest source)
Most women need supplementation: difficult to consistently get 400mcg from food alone, especially in early pregnancy when nausea limits eating.
Duration: continue throughout pregnancy. Most prenatal vitamins contain folic acid plus iron, B12, and other essentials.
Who should test: women trying to conceive should ask for serum folate test. Some doctors will test MTHFR status to choose the right form.
Read our full evidence-based guide on pregnancy for the complete picture.
View Full Guide →We write from peer-reviewed research and clinical guidance. These links let you read the underlying evidence yourself rather than taking our word for it.