Key Takeaways

  • Understanding the timing of ovulation in relation to your menstrual cycle is key to gauging the likelihood of pregnancy.
  • Sperm can survive up to 5 days in the uterus, so pregnancy is most likely when sex occurs close to ovulation.
  • Tracking your fertile window, the days leading up to and just after ovulation, can be achieved through strategies like the calendar method, monitoring cervical mucus, and tracking basal body temperature.
  • While fertility awareness methods can aid in family planning, they are more effective for achieving pregnancy than preventing it.

Sperm can live inside your uterus for up to 5 days after having penis-in-vagina sex, and pregnancy can only occur if there’s sperm in your uterus or fallopian tubes when you ovulate.

Ovulation typically occurs around day 14 of your menstrual cycle. But if your cycle is irregular or your calculations are off, having penis-in-vagina sex without a barrier method at other times of the month may still lead to pregnancy.

Ovulation occurs when your ovary releases an egg into a fallopian tube in anticipation of fertilization. The egg must experience fertilization within 24 hours, or it may begin to disintegrate, leading to menstruation or period-like bleeding.

Sperm must enter your vaginal canal and travel through your cervix, into your uterine cavity, and into your fallopian tube to fertilize the egg. Sperm can live inside your reproductive tract for up to 5 days in anticipation of meeting the egg.

If fertilization occurs, the egg must travel from your fallopian tube to your uterus and attach to your uterine wall. This generally takes place 6 to 10 days after ovulation.

Pregnancy is only possible if a fertilized egg implants in your uterus. If it doesn’t, your uterine lining can shed, and your menstrual period or period-like withdrawal bleeding can start.

Ovulation and menstruation are generally 2 weeks apart, so the likelihood of getting pregnant right before your period is low.

If you have a shorter cycle — the average is 28 days — pregnancy could occur if you have penis-in-vagina sex without a barrier method during or just after your period.

For example, if you have penis-in-vagina sex toward the end of your period and you ovulate early, you can conceive. Using conventional birth control is typically the best way to prevent pregnancy.

The closer your cycle gets to ovulation, the more likely you are to become pregnant during penis-in-vagina sex without a barrier method.

The 4 to 5 days leading up to ovulation, the day of ovulation, and the day after ovulation are often called your “fertile window.”

Tracking your fertile window can be a helpful way to time the sex you’d like to result in pregnancy or when to take precautions to prevent it.

Predicting your fertile window is another way to refer to fertility awareness methods or natural family planning. Several ways to track biomarkers commonly associated with your menstrual cycle include the following methods.

Calendar method

If you have a relatively straightforward or regular menstrual cycle, you may find tracking your monthly period or period-like bleeding helpful.

According to the American College of Obstetricians and Gynecologists, days 8 to 19 of a 26- to 32-day-long menstrual cycle are usually the most fertile.

The first day of bleeding is typically day 1 of your menstrual cycle. The number of days between the first day of consecutive periods is the length of your overall menstrual cycle.

Cervical mucus method

Cervical mucus is a type of vaginal discharge that can change throughout your menstrual cycle.

Many people notice an increase in thin, stretchy, or slippery discharge just before or during ovulation. Some people compare the consistency to raw egg whites.

Discharge usually becomes less noticeable after ovulation ends. It might feel sticky or appear thicker than before.

To get started, take note of the amount, consistency, color, and odor of your vaginal discharge at least once or twice per day.

Basal body temperature method

Your basal body temperature is your temperature when you’re fully at rest. It usually increases slightly, about 0.5°F (0.3°C), during ovulation and remains elevated until the end of your menstrual cycle.

Keeping a consistent temperature record using a special basal thermometer can help you track your overall ovulation pattern.

To get started, take your temperature every day as soon as you wake up — ideally before you engage in any activity in bed, get out of bed, or have anything to drink or eat.

It may take several months of tracking to reliably determine when you’re most likely fertile. Even still, there’s no guarantee that your calculations are 100% accurate.

If you aren’t trying to conceive, you may want to use a condom or another method to help prevent pregnancy.

Fertility awareness methods are 91% to 99% effective with great charting and implementation. Up to 9 out of 100 people who rely solely on fertility awareness methods to prevent pregnancy ultimately become pregnant.

If you consider human error, fertility awareness methods are only 76% effective. That means 24 out of 100 people who rely solely on fertility awareness methods become pregnant.

Tracking your fertile window is usually a more effective way to become pregnant than to avoid pregnancy.

Factors like stress, activity levels, and diet can all affect the number of days in your menstrual cycle, and the day you ovulate can change from month to month.

Depending on your fertility goals, you may find it helpful to consult with a healthcare professional about starting a more reliable form of birth control or preparing for potential pregnancy.