If a pregnancy has never occurred, the condition is called primary infertility, but if a couple cannot initiate another pregnancy after the birth of a first child, it is called secondary infertility. The causes of primary and secondary infertility may differ.
Infertility is fairly common, and about one out of every six couples is infertile at any given time.
A woman reaches the height of her fertility in her mid-20s. Her ability to conceive slowly declines until age 30 and drops more rapidly after that. A man's fertility decreases slowly until about the age of 40, and then decreases more rapidly. Women unable to conceive in their 30s should seek help more quickly than younger women because their chances of getting pregnant are declining more rapidly. A woman with a history of pelvic disease or a man who had mumps as an adult might also want to seek help quickly.