According to an article in Salon, "Rick Santorum may have eight children, but he married at 32". If Santorum did not use contraceptives until he was married, he was either: (1) celibate; (2) a sodomist; (3) the father of bastards; or (4) very lucky.
On the other hand, maybe Santorum did use them
Given his interest in everyone else's sexual behavior, it is fair game for the media to explore which of the above applies to Santorum