What supplement is recommended to be taken at least 3 months prior to pregnancy?

Folic acid is a crucial supplement recommended to be taken at least three months prior to pregnancy due to its significant role in fetal development. It is well-documented that adequate intake of folic acid before conception and in the early stages of pregnancy can help prevent neural tube defects, which are serious birth defects of the brain and spine. The neural tube forms in the first month of pregnancy, often before a woman even knows she is pregnant, making preconception supplementation particularly important.

In considering the other options, iron is important for preventing anemia, particularly during pregnancy, but it is not specifically recommended to begin prior to conception. Calcium supports bone health and is essential during pregnancy, but its supplementation generally can be initiated once pregnancy is confirmed. Vitamin D plays a role in immune function and bone health, yet it does not have the same specific target of preventing fetal developmental issues in the early stages as folic acid does. Therefore, folic acid stands out as the key supplement to initiate before pregnancy for the purpose of reducing risks associated with neural tube defects.