Fetal Position

Diego Velazquez
Venus, Spain

Stephen Wilkes's inverted version:

Definition: 

Fetal position (British English: foetal) is a medical term used to describe the positioning of the body of a prenatal fetus as it develops. In this position, the back is curved, the head is bowed, and the limbs are bent and drawn up to the torso.

This position is used in the medical profession to minimize injury to the neck and chest.

Sometimes, when a person has suffered extreme physical or psychological trauma (including massive stress), they will assume the fetal position or a similar position in which the back is curved forward, the legs are brought up as tightly against the abdomen as possible, the head is bowed as close to the abdomen as possible, and the arms are wrapped around the head to prevent further trauma. This position provides better protection to the brain and vital organs than simply lying spread out on the ground, so it is obvious as to why it is an instinctual reaction to extreme stress or trauma when the brain is no longer able to cope with the surrounding environment, and in essence "shuts down" temporarily.

The fetal position has been observed in drug addicts, who enter the position when experiencing withdrawal.

Many people assume this position when sleeping, especially when the body becomes cold.

http://www.artandpopularculture.com/Fetal_position

Symbolism: 

A character is seen in the fetal position before or after going through some kind of "rebirth": legs replied against the body, head close to the knees and arms crossed in front of the legs.

This is of course highly symbolic, this position being one of an unborn child. The character will also often be nude (for reasons like Naked on Revival or Out-of-Clothes Experience), and sometimes floating (in a void, in a liquid...) to better deliver the analogy with a baby in the mother's womb.

Here, "rebirth" is taken in a very general sense and can mean many things: ascending to a higher plane of existence, experiencing a great revelation, going through a massive physical transformation, healing after a very serious mangling, waking up after hibernation, etc.

It can be even be an actual birth if preceding a Reincarnation, or in the case of an Artificial Human or Clone.

To be clear, this trope doesn't concern every instance of a character curling in a fetal position, most likely after a traumatic event — the latter beingTroubled Fetal Position. Fetal Position Rebirth is used when illustrating a symbolic (re)birth or major upheaval for the personage.

http://tvtropes.org