This article is from the Infertility FAQ, by Rebecca Smith Waddell email@example.com with numerous contributions by others.
Unexplained: One of the most common forms of infertility is
unexplained. This is when no physical, hormonal or immunological cause
for infertility is found in either partner. Recent studies indicate
that some unexplained infertility may be related to the use of
non-steroidal anti-inflammatory drugs (NSAIDs), which impede
ovulation. Check http://www.fertilityplus.org/faq/nsaids.html for more