The Pill hasn't been shown to affect a woman's fertility negatively. Once a woman has stopped taking it, it's likely that her body will return to fertility very quickly. Some doctors recommend waiting until after the first post-Pill period to try to conceive so it's easier to figure out her cycle.
Some women do experience post-Pill amenorrhea and don't have a period for a few months after stopping their birth control regimen. Every woman is different, so her body may just be adjusting to the change in hormones. If three months pass with no period, she should see a doctor [source: Mayo Clinic].
It is true that women on the Pill may discover that they have ovulation problems that affect fertility only when they stop taking it -- the Pill can mask the symptoms of irregular or absent periods. But this method of birth control itself isn't the root of any fertility issues.