Infertility is the inability to conceive after one year of unprotected intercourse in a couple less than 30 yrs of age . If the couple is more than 35 yrs (female) then they should seek help after six months of unprotected intercourse.
Infertility is primary as well as secondary. In primary infertility, a couple has never conceived before but in a case of secondary infertility couple has conceived before but is unable to conceive now.
There are various factors which cause infertility. These can be a male factor, female factor, both male and female, unexplained.