Given the standard seven-year mating cycle, it is rare for Vulcans to seek or require contraception. The most common exceptions are for Vulcans who marry outside of the homo eridani subspecies of humanoid, Vulcans who may be required to perform sexually in the line of duty (undercover agents, particularly those impersonating Romulans), and Vulcans who may be in danger of rape (certain hazardous duty locales). In all of these cases, novacept has been made available upon request.
Pon farr, however, causes an additional complication to the contraceptive process for Vulcans which is not present in other humanoids. Pon farr is not just an uncontrollable urge to have sex -- it is an all-encompassing need to reproduce. The first Vulcans to have novacept implanted subdermally in their arms had a tendency to rip them out with their bare hands when the "blood fever" struck; in one case, death resulted when a major artery was severed and the Vulcan was too deep in pon farr to notice before going into shock from blood loss. A human named Julian Bashir, while interning at Starfleet Medical, proposed an ingenius solution: concealment. Doctors now hide the implant within a random bone (like a femur or rib) when giving novacept to Vulcans. The implant is shielded from standard medical tricorders, even though most Vulcans are unable to operate such equipment during the throes of pon farr. Doctors, of course, still know how to find them, for removal or recharge. Doctor Bashir referred to his idea as "a Low Jack type of system", which is possibly a reference to a Terran card game.