why women were designed for child bearing and not men?

Because the way we reproduce requires a sperm cell (from the male) to mix with (fertalize) an egg cell (from the female). This allows children to have different combinations of genes (a mix of the mother and father's) instead of being an exact copy of a single parent. So we can say that our sexual reproduction system needs three things:

One gender which produces eggs

One gender which produces sperm

One gender chosen to be the one in which the sperm fertalizes the egg, which means it needs to hold the growing baby which the fertalized egg turns into.

That's why males and females exist, and why the males and females have different characteristics. Men make sperm, women make eggs (well, actually they're made before the girl is born, but same thing for this purpose), and since sperm can swim and eggs can't, the sperm swims into the woman, fertalizes the egg and then the woman holds the baby until it's grown enough to survive by itself. Then, out it comes :) Reproduction has worked.

Let me clear one thing up - men were not 'given' the ability to make sperm nor women 'given' the ability to bear children. Men are men because they make sperm - that's why men exist. Likewise, women are women because they bear children - it's essentially the definition. Everything that makes a woman a woman is there BECAUSE she bears children - you couldn't have men bear children instead because you'd basically have to turn the man into a woman for it to make any sense.

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Oh, and for a quick answer based purely on logic: if men were given a womb instead of testes and a penis, and women were given testes and a penis instead of a womb; it would change nothing. Males and females would still exist, they'd just be swapped around, because having a womb is what makes you a female and having a penis and testes is what makes you a man. So if men were made for child bearing instead of women, men would be women and women would be men and you'd still be asking the same question :D

Also, by created you mean evolved.

The answer is fairly straightforward. Men are not designed for child bearing, because we need something to fertilize the egg inside the womb, and turn the egg into a child. If men were designed like that, there would be no men only women and in turn nothing to fertilize the egg and then we'd die out, due to our inability to reproduce. Basically guys are the key to turning eggs into babies, while the women carries that baby. We don't produce asexually so we need a partner, one to carry the baby and the other to help make the baby.

They say the two natural most painfull expierieces are toothache and childbirth .it is a proven fact women cope with pain better then men.

Because we're better at everything else besides child bearing.