High-Risk Women

Low Dietary Intake of Folate | Elevated Folate Requirement
Other Potential Risk Factors
| Motherisk Folic Acid Study

All women of childbearing age should take a daily multivitamin that contains a minimum of 0.4 mg (400mcg) of folic acid to reduce the risk of having a baby with a neural tube defect (NTD). For women in high-risk groups, that dosage should be increased to 4.0 mg of folic acid each day, after consulting with a doctor.

High-risk groups include:

  • women who have had a previous pregnancy affected by an NTD;
  • parents who have a personal or family history of NTDs;
  • women with insulin-dependent diabetes;
  • women who use certain anti-seizure medications;
  • women who are clinically obese;
  • women who abuse alcohol; and
  • women of Celtic, Northern Chinese, Cree and Sikh heritage.


At least 3 months Pre-Conception to 10-12 weeks Post-Conception
-Increased dietary intake of folate-rich foods
- 5mg of folic acid daily

12 weeks Post-Conception to 4-6 weeks after Birth (or throughout breastfeeding)
-Daily multivitamin containing 0.4-1mg folic acid

Vulnerable Women (e.g. on variable diet, no consistent birth control, possible substance abuse)
-Extra efforts at counseling re: prevention of birth defects and health
 problems through the use of folic acid and multivitamins

 A woman who has already had an NTD-affected pregnancy also has 20-times greater risk of giving birth to another child with an NTD.

Folic acid intake recommendations for certain high-risk groups can be found on the website for the Motherisk program at The Hospital for Sick Children.


Low Dietary Intake of Folate

Women cannot get enough folic acid from food alone, and low dietary intake of folate, which can lead to having a child with an NTD, can result from:

  • a poor quality diet;
  • chronic dieting and/or avoidance of foods containing folic acid (e.g., low carbohydrate diets);
  • low socio-economic status;
  • food selection and preparation methods that may be more common in specific ethnic groups (e.g., use of non-fortified rice as a staple, use of maize flour (masa) versus folic acid fortified wheat flour among certain Hispanic-Canadians, and prolonged stewing, a common practice among some South Asian-Canadians that destroys naturally occurring folate);
  • smoking; and
  • failing to take a multivitamin containing folic acid.

Consult our list of food sources of folic acid.


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Elevated Folate Requirement

To reduce the risk of having a child with an NTD, elevated folate requirements may be required where:

  • there is a personal or family history of NTDs or other congenital anomalies;
  • a woman is taking a medication that interferes with folate metabolism, including valproic acid, carbamazeprine or trimethoprim;
  • alcohol abuse;
  • malabsorption and gastric bypass surgery;
  • liver disease; and
  • kidney dialysis

Other drugs such as phenobarbitol, primidone, diphenylhydantoin, oxcarbamazepine, sulfonamides and methotrexate may increase the risk for other potentially folate-sensitive birth defects such as cleft lip and palate and heart defects) or increase NTD risks when combined with other drugs. Other medications known to elevate folate requirements include metformin, triamterene and barbiturates.

Where there is an elevated folate requirement, a higher dose of folic acid (greater than 0.4 mg per day) is recommended. However, clear instructions should be given by a health professional on when this higher dose should be started, changed or stopped.


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Other Potential Risk Factors

Additional risk factors that play a role in causing birth defects include:

  • obesity,
  • diabetes,
  • impaired glucose metabolism, and,
  • hyperinsulinemia.

In this case, a woman's red blood cell (RBC) folate concentration should be tested in order to determine the most appropriate dose of folic acid.

For additional details visit the Health Canada website, and speak with your health professional.

Health Canada, www.hc-sc.gc.ca, February 28, 2011.
American College of Physicians, www.acponline.org, February 28, 2011.


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Motherisk Folic Acid Study

Would you like to be paid for taking a multivitamin?

The Motherisk Program, located at the Hospital for Sick Children, invites women between the ages of 18 and 45 years to participate in a study about folic acid during pregnancy. Read more...


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