The diaphragm and cervical cap are latex or silicone cup-like devices that contain  spermicide and cover the cervix blocking the entrance into the uterus. They are put in place by the woman before intercourse. They can be inserted up to 1 hour before intercourse and should be left in place for at least 6 hours after intercourse. They require an  initial fitting and a prescription by a physician.

How Does It Work?
A spermicide is placed in the diaphragm or cap before it is inserted. The device is inserted deep into the vagina so that it covers the cervix, placing and holding the spermicide in place where is can be most effective.

Effectiveness
Generally the diaphragm is more effective than the cap  in practice as it is somewhat easier to insert and use properly. Ideally, for every 100 women using the diaphragm, approximately 6 will become pregnant each year. In practice, the number of pregnancies is closer to 15. For the cervical cap, the number can approach 30 per year.

Advantages
Advantage of the diaphragm and cap are:

• They do not effect a woman’s hormones
• Can be put in place in advance of planned intercourse
• Are relatively inexpensive
• Can be used while breastfeeding

Disadvantages
The disadvantages to the diaphragm or cap are primarily related to convenience:

• Must be inserted each time before intercourse
• Difficult for some women to insert
• Require refitting after childbirth
• Cannot be used during menstruation
• Some sexual activity can dislodge the device compromising effectiveness

Side Effects
There are few side effects with diaphragm or cap use. There can be some discomfort or pain during use. There are some women who develop frequent bladder infections with the diaphragm. Women who are allergic to latex or spermicides should not use the diaphragm or cervical cap.