How soon after starting birth control pills does it affect your period?

If you are taking oral contraceptives ("The Pill"), then you will get a period shortly after taking your final dose of the month. But the pill can disturb your hormonal balance, so if this is the first time you've ever taken oral contraceptives, you may not get one (or you may get a very mild one).

However, if you have had unprotected penetrative intercourse in the time running up to starting oral contraceptives, you could already be pregnant. Contrary to urban myth, oral contraceptives do not cause a miscarriage.

Therefore, if there is a risk that you may already have become pregnant before you began taking the pill, see your sexual health or family planning practitioner for confidential help and advice now, which should include a pregnancy test.