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When during your cycle can you have unprotected sex, without getting pregnant?
The fertility awareness method (also known as the rhythm method for natural family planning) can be a very effective way to prevent pregnancy if done correctly, if you have regular cycles, and if the timing is right. In order to maximize your chance of avoiding pregnancy with this method, it is important that you know 1) your cycle length 2) the days of your fertile window, and 3) your ovulation day. Knowing these pieces of information allows you to use condoms or avoid having sex during your fertile window and on ovulation day, and therefore better avoid pregnancy.
For context, cycle length is usually around 21-35 days, when counting the days between the first day of each period. Most people are most fertile 10 to 15 days after the first day of their period. As people near their fertile windows, libido typically increases, and vaginal fluid may become thin and watery. Ovulation, which is the release of a mature egg from the ovary, often occurs on the last day of the fertile window. From there, anywhere between 12-24 hours after ovulation, people are typically longer able to get pregnant because the egg disintegrates.
If you’re trying to use the fertility awareness method to avoid pregnancy, you may consider some fertility awareness aids to help you, like measuring your basal body temperature, monitoring your vaginal fluid, ovulation strips, or menstrual cycle tracking apps.