Limit children of Page in list

…searched and searched, can’t find it. I have a Page, and am listing the children of that page. This list will get too long eventually. I need to call only the latest 15 children of the parent. Right now I have:

<?php
  if($post->post_parent)
  $children = wp_list_pages("title_li=&child_of=".$post->post_parent."&echo=0");
  else
  $children = wp_list_pages("title_li=&child_of=".$post->ID."&echo=0");
  if ($children) { ?>
  <ul>
  <?php echo $children; ?>
  </ul>
  <?php } ?>

which is listing the pages nicely, but in some time, that list is going to get too long. Any way to limit it to the latest 15?

thank
JSC