According to the NHS, folic acid should be taken as soon as you start trying for a baby, ideally for three months before conception, and during the first 12 weeks of pregnancy. This helps a baby's brain and spine develop normally. Pregnant women can take folic acid after 12 weeks, and it helps produce red blood cells.
The usual dose is 400 micrograms daily, but a GP may prescribe a higher dose, typically 5 mg, if there is an increased risk of neural tube defects in the baby. A doctor or midwife may recommend continuing folic acid throughout pregnancy if you are anaemic or at risk of anaemia. There is no evidence that folic acid reduces fertility in either men or women.
You can take folic acid with or without food. Folic acid tablets should be swallowed whole with a drink of water. It remains unclear what specific epilepsy or antiretroviral medicines for HIV increase the risk of neural tube defects, and how exactly being very overweight or having sickle cell disease raises this risk.
Potential side effects or interactions with other medications or supplements are also not detailed.