How effective is the cervical cap as a contraceptive method?
If used perfectly the probability of failure during the first year of use for the cervical cap is 10 to 13 percent. The cervical cap has a substantially higher first year failure rate in women who have previously been pregnant because of difficulty in achieving an exact fit (26 to 27% failure in the first year). While consistent and correct use of these products is essential for effectiveness, approximately one-half of the failures of these methods occur despite diligent use. The Pearl index is 11-19/100 women years (failure rate for 100 women using the method for one year).
