It is possible to get pregnant soon after your period ends depending on how long your bleeding lasts, and when in your menstrual cycle you ovulate. If your periods are long, by the time it ends you may have few or no days left before your fertile days begin if you ovulate during the average days 12 to 14 of your cycle. Bear this in mind if you have unprotected intercourse right after you stop bleeding. If your periods are short, you have more days to go before you get to your fertile days and ovulation.
The Fertile Days in the Menstrual Cycle
The days of fertility in a menstrual cycle are fairly fixed and depend on when you ovulate rather than on whether your period has ended. The most likely day to get pregnant (fertilize an egg) is on the estimated day of ovulation. However, according to an important study reported in 1995 in the New England Journal of Medicine, you have five other fertile days before ovulation when you can get pregnant, making it a total of six fertile days in a menstrual cycle.
What the Additional Five Days Mean
The additional five fertile days mean that if you have intercourse during the five days before ovulation and sperm survives, you can still get pregnant, even if you don't have intercourse on the day of ovulation. This is because the sperm can survive in the reproductive tract for an average of three to five days and wait for the egg, according to Clinical Gynecologic Endocrinology and Infertility. Sperm may even survive for seven days. Because the egg can survive up to 24 hours after ovulation, it is also possible, though less likely, to get pregnant a day after ovulation.
How to Figure Your Fertile Days
The days you are fertile and can conceive during your menstrual cycle, if you have intercourse on any of those days, remain the same, whether your bleeding is long or short. The actual number of days depends on how long your menstrual cycles are and therefore, when in your cycle you ovulate.
If Your Cycles Are Twenty-Eight Days Long
If your cycles are the average, idealized 28 days long:
- You will most likely ovulate on day 14 (although it can be a day or two sooner or later), and your fertile window is from days nine to fourteen (six days).
- If you bleed the average five days, and you start having unprotected intercourse four days after your period ends, you can get pregnant.
- If you bleed for ten days, your fertile days are still days nine to fourteen. However, now you only have days 11 to 14 (four days) of fertility if you delay intercourse until after your period ends.
To be safe, you have to take into account that any estimation of the day you ovulate is not precise, and you could be a day or two off. Therefore, if you don't want to get pregnant, avoid unprotected intercourse or abstain until you are certain you are past ovulation.
Cycles Shorter Than Twenty-Eight Days
If your menstrual cycle lengths are shorter than 28 days, your fertile days will start before day nine of your cycle. For example, If your cycles are 24 days long:
- You will likely ovulate on day ten, and your fertile days will be from days five to ten (six days).
- If you bleed for five days, you can get pregnant if you start having intercourse as soon as your period ends.
- If you bleed for ten days and have intercourse the day after (day 11), you might still get pregnant if the egg you ovulated on day ten is still viable a day later.
Cycles Longer Than Twenty-Eight Days
If your menstrual cycle lengths are longer than 28 days, your fertile days will start after day nine of your cycle, and you have a longer window before you are likely to get pregnant. For example, if your cycles are 34 days long:
- You will likely not ovulate until day twenty, and your fertile days will be from days fifteen to twenty (six days).
- If you bleed for five days, you have a relatively safe window of ten days, from days six to 14, to avoid pregnancy if you have unprotected intercourse.
- If you bleed for ten days, your relatively safe window is reduced to five days, from days 11 to 15.
If Your Cycles Are Irregular
If your menstrual cycle lengths are irregular, the days you are fertile will vary from one cycle to another. In this case, you use can signs of fertility methods, such as tracking your temperature or your cervical mucus changes, to estimate when you might ovulate.
As explained above, your fertile window during which you can get pregnant will include the five days before your estimated day of ovulation and the day of ovulation - plus or minus a day or two. Each cycle, use this information to estimate how soon after your period ends you can get pregnant.
Knowing Your Fertile Window Is Helpful
If you are trying to get pregnant, knowing the days you are most fertile after your period ends will help you time intercourse to improve your chances of conception. On the other hand, if you are trying avoid pregnancy, this information will help you know when to abstain from intercourse or use birth control.
Your Fertility Window Is Only an Estimate
Keep in mind that the days you are most fertile are only estimates. This is because methods used to pinpoint the day of ovulation and the fertility window are not precise, and ovulation can vary by a few days each cycle, even if your menstrual cycles are regular. Therefore, using reliable birth control methods if you wish to avoid getting pregnant is essential.