The Spring Equinox, festival of Eostre (or Easter as we know it better), The Assumption of the Blessed Virgin Mary (March 25th now) are all connected.

The early Christian church wanted to nail some dates down (presumably so they could nail the barons for some extra money & gifts) so they looked at the existing festivals and chose accordingly. The spring Equinox/Eostre celebrated new life and rebirth. This, they decided, was the perfect time to celebrate the visitation of Gabriel to Mary and getting her up the duff. March 25th was chosen as the date that came closest to the existing festivals. This became known as Lady Day, and was possibly the first day of the new year. (When the 11 days was stolen at the changing from Julian to Gregorian calendars, this moved it to April 5th, which is what the Inland Revenue still use.)

Thus, with the annunciation fixed, they could settle Christmas, 9 months later, and conveniently enough, slap in the middle of several existing festivals.

Strictly speaking, in the UK it should be referred to as Mothering Sunday. It is always the middle Sunday in Lent, and that is a moveable feast. Mothers' day is just the abbreviated form of Mothering Sunday. However, there are countries that have a fixed date for honouring maternal parents (and more recently, paternal parents) and these are called Mothers' day.

Mothering Sunday should be used if the date is not fixed, Mothers' day if it is.

LTS

LTS