Why do most major birth defects occur during the embryonic stage?

Question

Quizplus · Accepted Answer

Most major birth defects occur during the embryonic stage because this is when the basic organs are being formed. Any errors or malformations during this stage can have a cascading effect on the development of the rest of the body. In contrast, during the fetal stage, the organs are mostly growing and maturing rather than being formed from scratch, so there is less opportunity for major defects to arise.

Why Do Most Major Birth Defects Occur During the Embryonic