How it works: A prescribed, one-size, reusable silicone rubber device is inserted into the vagina to cover the cervix. It must be used with spermicide, left in place eight hours after intercourse, and removed within 48 hours. You should replace it every six months.
Advantages: Secretions and air pass out of a central valve to create a tight suction; a loop makes the device easy to remove.
Risks: Irritation, urinary tract infection, and possible risk of toxic shock syndrome if used too long. Data on its failure rates is limited, but the FDA says 15 percent of women will get pregnant per year with perfect use.
Postpartum issues: Because this device was only recently approved by the FDA in March 2002, studies have not yet established that the shield is safe and effective after having a baby.
Cervical Cap (i.e., FemCap)
How it works: A prescribed, silicone rubber cup fits snugly over the cervix to keep sperm out. It must be used with spermicide, left in place at least six hours after intercourse, and removed within 48 hours. Replace it after one year.
Advantages: Spermicide can be placed on the inside and outside of the cap for added protection.
Risks: Irritation and allergic reactions, abnormal Pap test results, and toxic shock syndrome if worn too long.
Postpartum issues: Your gynecologist will need to prescribe a new size. The cap is less effective for women who have given birth vaginally: The typical failure rate doubles for women who have had children: 32 percent versus 16 percent in the first year.
How it works: The spermicide-saturated sponge covers the cervix. Leave it in place for six hours after intercourse. (After being off the market since 1995, the Today Sponge is again available, but by mail order only.)
Advantages: You can have protected sex for 24 hours, no matter how many times you have intercourse.
Risks: Irritation, allergic reactions, and toxic shock syndrome if worn too long.
Postpartum issues: The typical failure rate doubles for women who have had children: 32 percent versus 16 percent in the first year of use.