Here, during the same period, women, having given birth, were "tainted" and not accepted back into church for six weeks. After the time had passed they went to church on Sunday, knelt in front of the priest who said a prayer and they were once again welcome into society (also you could once more work out-of-doors, which was the important bit for farmer's wives). IIRC it has it's roots in Genesis.

I've always taken confinement to mean something similar to this, but perhaps the CofE had no such tradition.

] In the Regency period, the period of labor and childbirth itself, and the following few days or weeks (when the woman would often confine herself to her room, or to her house), were the "confinement"