Question for Betty.
 

Dear Betty,

Can you get pregnant while on birth control and if so, when would you know?  My boyfriend and I don't use condoms.

 
Betty's Answer.
 

Dear Reader,

Oral contraceptives (birth control pills) have a low pregnancy rate if they are taken properly, less than 1 pregnancy in the first year of use per 100 women.  However, the actual pregnancy rate (8 pregnancies in the first year of use per 100 women) is much higher because many women forget to take the pill (OCs) everyday. Pregnancy while taking oral contraceptives may be due to: method failure (lack of OC efficacy), patient failure (omission of OCs), or concurrent use of other drugs (such as certain antibiotics).  Women who smoke have an increased chance of becoming pregnant while using OCs.  Women who are overweight also have an increased risk or pregnancy.
The possibility of pregnancy must be considered for women whose menses have not occurred after the first cycle of OCs or after 45 days from their last menstrual period.  If you have been on OCs for awhile and have missed 2 consecutive menses, it is time to take a pregnancy test.