In times of distress, people often curl up over their abdomen in what is called the fetal position because it is the most instinctive way to protect the most important organs of the body. This is the same position babies take in the womb, thus the name.
The fetal position is said to be a product of human evolution. People assume this position in times of distress because it reminds the body of the safest, most comfortable period of its existence: the time it spent gestating in the womb. It serves many practical purposes, such as protecting the head and the heart and minimizing danger to the body by keeping it as unexposed as possible.