RECOMMENDATIONS ON THE USE OF FOLIC-ACID SUPPLEMENTATION TO PREVENT THE RECURRENCE OF NEURAL-TUBE DEFECTS

Objective: To prevent the recurrence of neural tube defects (NTDs) in families at increased risk of having offspring with NTDs with the use of periconceptional folic acid supplementation. Options: Genetic couns elling and prenatal diagnosis of NTDs. Outcomes: NTDs cause stillbirth , neonatal death and severe disabilities. The cost for medical care an d rehabilitation in the first 10 years of life of a child with spina b ifida cystica was estimated to be $42 507 in 1987. Evidence: The autho rs reviewed the medical literature, communicated with investigators fr om key studies, reviewed policy recommendations from other organizatio ns and drew on their own expertise. A recent multicentre randomized co ntrolled trial showed that among women at high risk of having a child with an NTD those who received 4 mg/d of folic acid had 72% fewer case s of NTD-affected offspring than nonsupplemented women. Two previous i ntervention studies also demonstrated that folic acid supplementation was effective in reducing the rate of NTD recurrence. Several retrospe ctive studies support this conclusion. Values: Recommendations are the consensus of the Clinical Teratology Committee of the Canadian Colleg e of Medical Geneticists (CCMG) and have been approved by the CCMG Boa rd. The committee believes that primary prevention of NTDs is preferab le to treatment or to prenatal detection and abortion. Benefits, harms and costs: Folic acid supplementation should result in fewer NTDs amo ng infants in Canada and ancillary savings in medical costs. The recom mended dosage of folic acid is not known to be associated with adverse effects. Higher dosages of folic acid may make vitamin B-12 deficienc y difficult to diagnose and may alter seizure frequency in patients wi th epilepsy due to drug interactions with anticonvulsants. Recommendat ions: A minimum dosage of folic acid of 0.8 mg/d, not to exceed 5.0 mg /d, is recommended along with a well-balanced, nutritious diet for all women who are at increased risk of having offspring with NTDs and who are planning a pregnancy or may become pregnant. Supplementation shou ld begin before conception and continue for at least 10 to 12 weeks of pregnancy. Validation: These guidelines are similar to those of the S ociety of Obstetricians and Gynaecologists of Canada, the US Centers f or Disease Control and Prevention and the Department of Health in Brit ain. Sponsors: These guidelines were developed by the CCMG Clinical Te ratology Committee and endorsed by the Board of the CCMG. No funding f or the development of these guidelines was obtained from any other sou rces.