However this is year 2012 and anytime a couple are expecting a child they always know the sex of the baby by the 2nd trimester.
In all honesty I think 80% of couples always find out the sex of their babies before its birth.
These two statements don't go together.
What I mean is in year 2012 which is the time we live now present , most couples already know the sex of their baby by the 5 month of the pregancy.
I've highlighted the contradiction (always vs 80%). chardman and I have offered data that indicates that even 80% is too high.
Regardless of the exact figure, I've also offered proof that there are really people who reject finding out their baby's gender before birth. So have other posters.