Barrier methods of birth control 

male condom - This is a single use cover for the penis which prevents semen from entering the vagina. They are commonly made of latex and synthetic material and help prevent the spread of infections. Condoms made of lambskin, i.e. " natural " condoms, can help prevent pregnancy but do not prevent against infections like HIV or chlamydia. All condoms are weakened by oil based lubricants. Several times a year I see babies conceived during condom use.

female condom - This is basically a plastic bag which is inserted into the vagina to prevent semen from entering. It can be inserted up to 8 hours in advance. 

diaphragm or cervical cap - These are small flexible dishlike devices which are filled with spermicide and then placed over the cervix before intercourse. They must be left in place for at least 6-8 hours after intercourse. They come in different sizes and must be fitted to each patient. 

spermicide - This is available in a variety of different forms and available over-the-counter without a prescription. They are placed in the vagina no more than one hour before intercourse and must remain there at least 6-8 hours after intercourse.