Folic acid is a water-soluble vitamin of the B group. It is found naturally in green vegetables, legumes and citric fruits. It is actively secreted in breast milk with concentration higher in mature milk compared to colostrum (Cooperman JM, Dweck HS, Newman LJ, Garbarino C, Lopez R. The folate in human milk. Am J Clin Nutr. 1982;36(4):576-580).

Folic acid 400 micrograms per day is recommended in the first 12 weeks of pregnancy to prevent neural tube defects. If the mother is on anti-epileptic medication, is obese (BMI >30), has a history of neural tube defects in a previous pregnancy, has coeliac disease, diabetes, sickle cell anaemia, thalassaemia, she or her partner have spinal cord defects, the dose should be increased to 5 mg daily.

If the mother is continuing to breastfeed an older baby, she can take the dose of folic acid to protect the unborn baby. No harmful effects have been observed by taking folic acid during lactation (https://e-lactancia.org/breastfeeding/folic-acid/product/). Excess of folic acid is eliminated by the kidneys every day.

Mass media campaigns have been successful in increasing folate awareness but in no study has the post-campaign rate of folic acid use exceeded 50%. It has been recommended that all women of childbearing age should take folic acid regularly on the assumption that they might become pregnant (NICE PH11). Currently neural tube defect affected pregnancies arise in 0.8 per 1000 pregnancies, which translates to 800 pregnancies each year in the UK.