What does Boxing Day have to do with boxing?
1768, with -al (1) + Latin puerperus "bringing forth children; bearing a child" (as a noun, "woman in labor"), from puer "child, boy" (see puerility) + parere "to bear" (see pare). Earlier puerperial (1620s).
puerperal pu·er·per·al (pyōō-ûr'pər-əl)adj. Relating to, connected with, or occurring during childbirth or the period immediately following childbirth.