From The Don't Screw With The Natural Law Department:

Oral contraception linked to prostate deformities


New Scientist provides the details:


Oestrogen-like chemicals commonly found in oral contraceptives and plastic packaging could deform the prostate gland of human embryos, suggests a new study in mice. Deformities to the prostate gland have been linked to prostate cancer and bladder disease in later life.
The finding is significant because up to 3% of women taking oral contraceptive drugs become pregnant without their knowledge, and continue exposing the fetus to the contraceptive drug many months into pregnancy.

In the immortal words of Victor Buono, "What you don't know can hurt you a whole lot." (This quote is from "The Exorcists" - Episode #82 of one of the greatest TV series ever, The Odd Couple. Mr. Buono played Dr. Clove.)