R moshe notes relationship bet. tumas leidah & bris 8th day (on shabbos). Even before 1st positive step in chinuch parents must have awareness that just coming into this world & just by a body coming into existence, the natural state is tum'ah. After the cautios awareness of the nature of our bodies & the world we're in, they can then begin the positive chinuch w bris.
on the other hand, we find also the opposite - that for 33 days following the bris any blood which normally is considered severe tumah is reversed to 'dam tohar'. (all the more so acc. to mayan echad). from this we learn that the proper training of even one child has the power to affect & completely reverse not just himself but even (others) his surroundings.
