How soon after stopping birth control can I become pregnant?

There is no evidence that there is increased risk of spontaneous abortion increases if a woman becomes pregnant in the first cycles after stopping oral contraceptive pills. Intrauterine devices (IUD's) are not harmful to the fetus. Women who get pregnant with an IUD that is still in place do not have higher change of congenital abnormalities in the fetus compared to other women. If the IUD of a woman in her 1st trimester is carefully removed by a doctor, or if it is expelled on its own in the 1st trimester, the chance of spontaneous miscarriage is not increased compared to other women.
When barrier methods such as condoms, diaphragms, cervical caps, and sponges are used, pregnancy can occur by simply discontinuing their use during a regular cycle. The same can be said for spermicidal gels and suppositories. For more information about birth control, please read the Birth Control article.
Medroxyprogesterone (Depo–Provera) is an injectable hormone used for contraception. The contraceptive effect of Depo–Provera may last as long as 18 months after the last injection. Normal menstrual cycles and pregnancy cannot occur until after the contraceptive effect wears off.