As Christianity spread, pagan holidays were often incorporated into Christianity in order to ease the transition.
This is well documented historically and includes things like Christmas (winter solstice…) and Easter.
Eastrus was a pagan fertility goddess. Symbols of fertility include eggs and of course rabbits… so when the pagan fertility holiday was co-opted, eggs and rabbits were incorporated as well.
This can also be related to the term estrus - meaning n. The periodic state of sexual excitement in the female of most mammals, excluding humans, that immediately precedes ovulation and during which the female is most receptive to mating; heat.
The Christians took the fertility and altered it to be a holiday celebrating the end of death and resurrection (the end of winter, and the beginning of the life with the fertility of spring).