Guidelines generally recommend that women start getting Pap smears at age 21 and continue every three years until age 65. Women aged 30 and older may opt for a combination of a Pap smear and an HPV test every five years, as the human papillomavirus is a major cause of cervical cancer. However, these recommendations may vary based on specific risk factors, including a history of cervical cancer or pre-cancer, HIV infection, or a weakened immune system.