Taking Folic Acid Before You Get Pregnant: Recommendations for Folic Acid to Prevent Neural Tube Defects

Recommendations for Folic Acid to Prevent Neural Tube Defects

A randomized controlled multicenter trial in Britain has shown that periconception folic acid supplementation can decease the risk of recurrent neural tube defects (NTD) by 72%. More recently a Hungarian trial demonstrated a reduction in the first occurrence of NTD when women took a multivitamin supplement including 0.8 mg of folic acid. There were no neural tube defects among 2104 treated patients, whereas there were 6 among 2052 controls. Following these reports the Centres for Disease Control and Prevention in the USA recommended that "all women of childbearing age in the United States who are capable of becoming pregnant would consume 0.4 mg of folic acid per day". The Society of Obstetrics and Gynecology of Canada and the Canadian College of Medical Genetics recently published recommendations and these are summarized in the table below.

We would like to emphasize that since the neural tube is formed between 16-28 days post-conception (at a time when many women are not aware of their pregnancy) it is of utmost importance to start the folic acid supplementation a month prior to conception and continue it during the first trimester of pregnancy. A normal, balanced diet does not supply the daily recommended amount of folic acid.

Suggested folic acid supplementation for the prevention of NTD.

Risk for NTD	Amount *
General Population Risk	0.4-0.8 mg/day
Increased Risk 1. Previous pregnancy with NTD 2. A relative (living or dead) with NTD 3. ~ Women with epilepsy on valproic acid or carbamazepine 4. Women with IDDM not controlled prior to conception	0.8-5 mg/day 0.8-5 mg/day 0.8-5 mg/day 0.8-5 mg/day

Folic Acid Availability in Singles Entities in Canada

Brand Name (Manufacturer)	Folic Acid (mg)
Folic Acid (Finlandia; Gernetic; Jamieson; Kripps; Lee-Adams; Swiss- Herbal; Trophic; Vita Health) ApoFolic (Apotex) Foldine (Suisse Inc. Les Produits Naturels) Folvite (Lederle) Novofolacid (Novopharm) Folic Acid (Adams; Drug Trading Everest; ICN; Kripps; Pro Doc; Regal; Sands; Stanley)	1 mg 5 mg 5 mg 5 mg 5 mg 5 mg

* Precautions: Pernicious anemia must be ruled out, as hematological effects may be corrected by using folic acid, but neurologic damage will progress due to persistent vitamin B12 deficiency. Convulsions may occur in previously controlled epileptic patients.

David Chitayat, The Prenatal Diagnosis Program
University of Toronto