'Thank God I'm not a woman' or whatever that Jewish prayer is/was. Male identity is largely shaped by 'not being' something. What that is is not being a woman, and moving out of the family world of women and children to become a (real) man. The final bastion of separate identity is the power of representing God. If women actually are seen as representing God then men are really not 'separate but more equal', which is what their identity has largely been built on. They are actually then 'less equal' in their own eyes because they can't give birth. That's one reason they push the strange analogy that 'women can't be priests like men can't give birth', which really makes no sense at all.