Ecclesiastes 6:3-5 reads from the New American Standard:
3)If a man fathers a hundred children and lives many years, however many they be, but his soul is not satisfied with good things and he does not even have a proper burial, then I say, "Better the miscarriage than he, 4) for it comes in futility and goes into obscurity; and its name is covered in obscurity. 5) "It never sees the sun and it never knows anything; it is better off than he."
This text is clearly comparing the quality of life of the unborn with someone that can't appreciate life, and makes the statement that the unborn have it better in such cases. Please read all of Ecclesiastes chapter 6 to see that I am applying this text in context.
The word "abortion" is a modern term. For the bible to apply to abortion, ancient equivalents have to be established (otherwise the bible makes no statements regarding abortion at all, for OR against!). With that said, the word "miscarriage" is also translated in various bibles as "premature pregnancy", "stillborn", "pregnancy ending before its time", or similar terms. All of these terms can refer to ending a pregnancy through natural or induced methods. So, it is responsible to conclude abortion is covered by this passage in the context of modern times.
Also, notice that the scripture specifically says that the unborn "never knows anything". Other translations use the words, "not conscious of anything" or similar wording. This is exactly opposite of what Christian Fundamentalist try to claim. These people obviously don't read the bible for themselves, otherwise, this scripture would be paramount in their various religions and I wouldn't have to correct them now. Ironically, by saying that the unborn "never knows anything", this scripture indirectly supports a Pro-Choice point-of-view.