But note that the fertile window displayed in Clue is an estimate, and not your true biological fertile window you'll need to take measurements like basal body temperature or ovulation tests to know when you ovulate each cycle. Douching — that is, squirting water or other liquids into the vagina to rinse it out — is not a good way to prevent pregnancy because it will not remove all sperm. It's a common belief that you can avoid getting pregnant if you rinse or wipe your vagina right can a woman get pregnant by anal sex. Also, the consistent use of condoms can help prevent the spread of STIs. By following careful rules that combine the changes in BBT with carefully-tracked changes in cervical mucusyou can estimate the days in your cycle when you have the highest likelihood of becoming pregnant 9. Most antibiotics will not interfere with your hormonal birth control method.