20/09/2026
Folic acid: the dose, the timing, and who needs 5mg 🌱
Very little in preconception medicine carries the weight of evidence folic acid does, which makes the details worth getting right.
The standard dose is 400 to 800 micrograms daily, started at least four weeks before you begin trying and continued through the first twelve weeks of pregnancy. Starting before matters because the neural tube closes by around 28 days after conception, often before a positive test. Starting when you find out is starting after the window.
Some people need 5mg, more than ten times the standard dose. That includes anyone taking anticonvulsants, anyone with diabetes, anyone with a previous neural tube defect, a BMI over 30, or a malabsorption disorder.
5mg is prescription strength. It is not a matter of taking more of your supermarket supplement.
If any of those apply to you, ask your GP about the high dose 🩺