Confinement...

I don't know what cultural/religious reasons there may be about
'confinement' but like so many religious/cultural practises, it's based
pretty much on common sense. By the time you get to the last month
of pregnancy, so-called confinenent is simply a sensible idea since
there's no telling when your baby will decide to come into the light,
and being home alone at that moment, is not a good idea!

Besides, the fact is that by that time you feel like the size of a cow
and about as mobile and elegant, so you're pretty limited in how
much you can get around, up and down stairs, carrying heavy
packages etc. which all place a tremendous strain on your system at
this late stage.

Emotionally you also feel the need for a stable and emotionally
supportive environment: something traditionally your parents (mostly
mother) can offer you. Likewise, post partum, you need as much help
as you can get, traditionally provided by the grandmother, sisters,
aunts, etc.

These days, of course, as pre and post natal care in the so-called
developed world has advanced so much, there's no real reason to
confine yourself to home in case of medical emergency. But in many
rural areas and ancient cultures, the custom is still practised, and I
believe provides a far more worthwhile and enriching experience
than many modern 'advances'.