fetal position

plural fetal positions · alternative foetal position

1. literallyThe location of the fetus inside a womb.
2. A posture in which the head and knees are brought close to the abdomen, usually while sitting or lying on one side.

   The fetal position is the most common sleeping position.

   1 more example

   When life's stresses get to be too much ... and my pacifier and thumb don't cut it ... there's only one thing for me to do. Return to the fetal position.

   2013 February 1, Tom Armstrong, Marvin (comic)