I think the question of why Elves did not have very large families could be answered by considering that as they are immortal, if they continued having children throughout their lives, the Elven population would simply be too large and unsustainable. Perhaps the Elves knew this, and with their love of the natural environment might also have realised what a strain on resources that would become, as in our own world.
In Morgoth's Ring I believe it also states that once an Elven couple had completed their family, the main joy that they had from marriage was companionship:
Quote:
|
with the exercise of the power the desire soon ceases, and the mind turns to other things. The union of love is indeed to them great delight and joy, and the 'days of the children', as they call them, remain in their memory as the most merry in life; but they have many other powers of body and of mind which their nature urges them to fulfil.
|
and
Quote:
|
It might be thought that, since the Eldar do not (as Men deem) grow old in body, they may bring forth children at anytime in the ages of their lives. But this is not so.For the Eldar do indeed grow older, even if slowly; the limit of their lives is the life of Arda, which though long beyond the reckoning of Men is not endless, and ages also. Moreover their body and spirit are not separated but coherent. As the weoght of the years, with all their changes of desire and thought, gathers upon the spirit of the Eldar, so do the impulses and moods of their bodies change.
|
Also, in times of war Elves endeavoured not to have children, indeed, not to marry, and the history of Middle Earth is peppered with conflict which might reduce the potential population.
So with such considerations, it might be expected that Elven bodies are also made a lot differently to human bodies.