If you are trying to conceive, you should already be taking folic acid - and continue to do so until the end of the 12th week of pregnancy.
The current advice is to take a daily 400mcg supplement, to help protect your baby from neural tube defects such as spina bifida.
Research also suggests that taking folic acid before getting pregnant means your baby is likely to have a higher birth weight.
This is good because low birth-weight babies (less than 5lb 8oz) are at higher risk of developing infections, and are more likely to suffer from heart disease and diabetes as adults.
Visit our sister site netdoctor.co.uk for more information on folic acid.