Recurrent pregnancies during oral contraception.

The records of the Royal College of General Practitioners' Oral Contraception Study were examined for those women who had become pregnant while using combined oral contraceptive pills. Analysis reveals that these women are much more likely than average to have further failures if they resume taking the Pill (seven failures in 35 women-years, compared with one in 500 women-years for the whole study). This finding could occur through some factor in the patient's personality (patient failure) or through some factor in the patient's metabolism.