How Soon After Your Period Can You Get Pregnant?
Sperm can live inside your uterus for up to five days after having sex, and pregnancy can only occur if there are sperm in your uterus or fallopian tubes when you ovulate.
For many women, ovulation occurs around day 14 of your cycle. However, having unprotected sex during your period or outside of your expected fertile window isn’t a guarantee that you won’t get pregnant.
For women with a shorter cycle — the average is 28 to 30 days — there’s still a possibility pregnancy could occur if you have sex during your period. For example, if you have sex toward the end of your period and you ovulate early, you can conceive. Using birth control, condoms, or another method of protection is always the safest way to prevent pregnancy.
Read on to learn more about how to time sex and other ways to prevent pregnancy.
How do ovulation and pregnancy work?
Ovulation occurs when a mature egg is released from an ovary. About once a month, an egg matures and is released into the fallopian tube. It then heads toward waiting sperm in the fallopian tubes and uterus.
An egg is viable between 12 and 24 hours after it leaves the ovary. Sperm can stay alive up to five days after having sex. Implantation of an egg, which happens after fertilization, usually takes place 6 to12 days after ovulation.
You can get pregnant immediately after your period. That can happen if you have sex toward the end of your cycle and are approaching your fertile window. On the other hand, the probability of getting pregnant right before your period is low.
If you’re tracking ovulation and wait 36 to 48 hours after ovulating, the chance you’ll conceive is low. The probability for pregnancy decreases the further in the month you are from ovulation.
If pregnancy doesn’t occur, the uterine lining will shed and your menstrual period will start.
Tracking your fertile window
Tracking your fertile window is a way to determine your “optimal” time to get pregnant. It can also help prevent pregnancy if you aren’t trying to conceive. As a method of reliable birth control, it can take several months of recording your monthly cycle to figure out your fertile window.
How to track your fertile window
The following method will help you find out your fertile window.
For 8 to 12 months, record the day you start your menstrual period and count the total number of days in that cycle. Note that the first full flow day of your menstrual period is day one.
Then write down the longest and shortest number of days from your monthly tracking.
Find out the first day of your fertile window by subtracting 18 days from the length of your shortest cycle. For example, if your shortest cycle was 27 days, subtract 18 from 27, and write down day 9.
Find out the last day of your fertile window by subtracting 11 from your length of the longest cycle. For example, if it was 30 days, you’d get day 19.
The time between the shortest and longest day is your fertile window. In the above example, it would be between days 9 and 19. If you’re trying to avoid pregnancy, you’d want to avoid having unprotected sex during those days.
How to use your fertile window as birth control
Ovulation will occur one day during your fertile window. The egg released is viable for 12 to 24 hours. That doesn’t mean you can get pregnant every day during this window. But if you’re trying to prevent pregnancy, you should abstain from unprotected sex during the entire fertile window.