What is the primary risk factor for congenital heart defects (CHD) and neural tube defects (NTD) in pregnancy?

From the Guidelines

The primary risk factor for congenital heart defects (CHD) and neural tube defects (NTD) in pregnancy is a folate deficiency, particularly in the preconceptional period. To mitigate this risk, pregnant women or those planning to become pregnant should take folic acid supplements at a dose of 0.8 mg (800 μg) daily, starting at least one month before conception and continuing through the first 2 to 3 months of pregnancy 1. Key considerations include:

• The use of certain antiseizure medicines and a personal or family history of neural tube defects are well-established risk factors for CHD and NTD 1.
• Other reported risk factors include mutations in folate-related enzymes, maternal diabetes, and obesity 1.
• For women with higher risk factors, such as a previous pregnancy affected by neural tube defects, a higher dose of folic acid may be recommended under medical supervision.
• In addition to supplements, women should consume folate-rich foods like leafy green vegetables, legumes, and fortified grains to support fetal development.
• Folic acid is crucial for proper fetal development, particularly during the early weeks of pregnancy when the neural tube and heart are forming, helping prevent neural tube defects like spina bifida and anencephaly, as well as certain congenital heart defects 1.
• Starting supplementation before pregnancy is important because neural tube closure occurs very early, often before a woman knows she's pregnant, ensuring sufficient folate levels during this critical period of fetal development 1.

From the Research

Risk Factors for Congenital Heart Defects (CHD) and Neural Tube Defects (NTD)

• The primary risk factor for CHD and NTD is a lack of folic acid supplementation before and during pregnancy 2, 3, 4, 5, 6
• Women with a previous history of NTD-affected pregnancy, family history of NTD, periconceptional antiepileptic drug exposure, pregestational diabetes, and prepregnancy obesity are at higher risk for NTD 2
• Women with a family history of CHD should discuss prenatal use of folate supplementation with their obstetricians prior to becoming pregnant 5
• Other risk factors for NTD include:
  • Not being in a marital relationship 6
  • Previous history of abortion or stillbirth 6
  • Inadequate housing conditions 6
• Protective factors for NTD include:
  • Folic acid or multivitamin supplementation early in pregnancy 2, 3, 4, 6
  • High-dose folic acid supplementation for women with a previous history of NTD-affected pregnancy or family history of NTD 2, 4
  • Fortification of staple food with folic acid 3

Folic Acid Supplementation

• The recommended daily dose of folic acid for women of childbearing age is at least 400 μg 2, 3, 4
• Women with a previous history of NTD-affected pregnancy should consume 4,000 μg of folic acid daily 2, 4
• High-dose folic acid supplementation may be beneficial for preventing CHD 5