Childbearing women have always bled once a month and many cultures would have women withdraw from everyday life during those times. They would use this time to meditate and renew themselves mentaly and physically. Very early blood offerings were freely given menstrual blood as a symbol of rebirth, but over time it became viewed as contaminating rather than sacred.
'Stupid' and self-centred men without any empathy for this process connected blood with death (in order for blood to flow, a living creature had to die). Thus, menstruation came to be seen as a consequence of death, and deemed unclean. You can see this happening in Leviticus where phohibitory laws were developed that dehumanised and isolated women.
We're said to be made in the image of God, but I don't think this means we or He are in three separate parts. Nor do I think that God had two arms legs and ugly bits under his loin clothes.