Is it bad to take fertility pills without knowing if you have fertility problems ?

Yes - it is: It is never a good idea to take medicine without "indication" ( there being a specific reason).

Determine need befor: Fertility drugs improve chances of pregnancy by stimulating the ovary, either directly or indirectly through brain, to produce eggs. Since by using these drugs, more eggs may be produced, multiple births like twins or triplets may result with pregnancy with complications like miscarrriage etc. You should give yourself a reasonable period for natural conception before before fertility drugs.