Does a pregnant woman who has a parent with a neural tube defect need more folic acid?

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Some women may require more folic acid when their baby is at moderate or high risk of having a neural tube defect or other birth defects related to folic acid. Family history on the 1st or 2nd degree (eg parents, grandparents, siblings) is a moderate risk factor.

Health Canada recommends that all pregnant women or women who wish to become pregnant take a multivitamin containing 0.4 mg of folic acid (English version to follow) daily to prevent neural tube defects. However, women whose babies are at higher risk may need a larger dose.

Pregnant women should consult a health care professional about this if they present any of the following:

  • Neural tube defect in a previous pregnancy
  • Personal history or spouse with a neural tube defect
  • Family history of neural tube defects in the 1st or 2nd degree (eg parents, grandparents, siblings, uncles, etc. This includes the parents of the spouse)
  • Diabetes type I or II
  • Personal or family history of other birth defects related to folic acid (certain heart defects, cleft lip, etc.)
  • Anticonvulsant drugs or other medications that affect folic acid levels
  • Intestinal malabsorption, which decreases the absorption of folic acid (eg Crohn’s disease, active Celiac disease, advanced liver disease, bariatric surgery, dialysis, alcohol abuse).

In the presence of type I or type II diabetes, or when certain drugs are taken during pregnancy, it is recommended to ask a doctor if the folic acid requirements are thereby increased. If there are birth defects in the pregnant woman or a family member, it is relevant to ask a doctor if this is a folic acid-sensitive anomaly, in which case a lack of folic acid can represent a risk factor for the development of this abnormality in the baby.

It is important to note, however, that it is not recommended to take more than 1 mg of folic acid daily without prescription, because high doses of this vitamin can mask a vitamin B12 deficiency. Concretely, this means do not exceed the recommended dose of a multivitamin daily. If folic acid addition is necessary, it can be taken in a single pill, always under medical advice.


Directive Clinique de la SOGC. (2015). Supplémentation préconceptionnelle en acide folique / multivitamines pour la prévention primaire et secondaire des anomalies du tube neural et d’autres anomalies congénitales sensibles à l’acide folique. Journal of Obstetrics and Gynaecology Canada, 37(6), S1-S19.

Santé Canada. 2010. Supplémentation plus élevée en acide folique – questions et réponses destinées aux professionnels de la santé.


Agence de la santé publique du Canada. (2008). Pourquoi toutes les femmes qui pourraient devenir enceinte devraient prendre de l’acide folique ?

Baby Center. (2011). L’acide folique, un supplément essentiel.


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