Final answer:
Excessive consumption of Vitamin A during pregnancy is most significantly associated with birth defects, whereas folic acid is vital for preventing neural tube defects. Pregnant women must manage their intake of Vitamin A to prevent teratogenic effects.
Step-by-step explanation:
The micronutrient most significantly associated with birth defects when consumed excessively during pregnancy is Vitamin A. While folic acid is critical to prevent birth defects, especially neural tube defects such as spina bifida, it is the excessive consumption of Vitamin A that poses a high risk for teratogenic effects, potentially leading to birth defects.
Pregnant women should be cautious with Vitamin A intake because it is a fat-soluble vitamin, which means it can accumulate to toxic levels in the body more easily than water-soluble vitamins. High levels of Vitamin A can harm an unborn baby, leading to congenital malformations. It is essential for pregnant women to manage their intake of this vitamin through diet and supplementation carefully.
On the other hand, folic acid is highly recommended for women of childbearing age and during pregnancy to reduce the risk of birth defects. Sources of folic acid include leafy green vegetables, whole wheat, fruits, nuts, and legumes.