Probability of Getting Pregnant During Your Cycle

Ever thought it was easy to get pregnant after a single romp? Yeah, that’s what many of us were made to believe in high school. But in practice, it might take a little more time and effort to increase your chances of getting pregnant.

Now, let’s get a little mathematical. No worries if you’re averse to math. I’ll attempt to make this as simple as possible.

Remember the classic probability question of rolling a number X on a dice after N attempts? Let’s say we’re trying to roll a “1” on a dice and we have three attempts. To calculate this, lets calculate the probability that we never roll a “1” across the three attempts.

This gives us the following: 5/6 x 5/6 x 5/6 = 125/216 or 57.87% chance of never rolling a “1” across three attempts.

Therefore, the probability of rolling a “1” at least once across three attempts is 1 – 125/216 = 0.4213 (a 42.13% chance).

Let’s try to apply this logic to real life. If you have an average cycle (say 28 days), you have a fertile window of six days. So, your chances of conceiving during every cycle is 1/6 (or 16.67). Hypothetically, your chance of conceiving after three cycles is about 42%.

What Are Your Odds of Conceiving at Every Point in Your Menstrual Cycle?

Timing is king when it comes to making a baby. Not sure about when to baby dance to increase your chances of conceiving? Read on.​

Can You Get Pregnant During Your Period?

Simply put, your odds of conceiving during menstruation are nearly zero. Why? 

During your period, the inner lining of your uterus is being shed. In most women, menstruation lasts between three and seven days. 

The Menstrual Cycle

By day three of your cycle, your progesterone and estrogen levels start increasing and estrogen initiates the formation of a new layer of endometrium, preparing it in case of fertilization. Around day four of your cycle, follicles begin to mature in your ovaries.

If you have an average cycle length, the window of ovulation is day 11 through day 21 of your cycle. So, technically, you cannot ovulate while menstruating.

However, if you have a very short cycle (approximately 21 to 24 days) you typically ovulate sooner in your cycle. 

Note that a period should not be confused with ovulatory bleeding. Some women–especially those whose cycles are very irregular–experience mid-cycle or ovulatory bleeding. This occurs around ovulation and the blood can be either dark brownish red color or pink. 

A woman who has ovulatory bleeding will bleed lightly and the blood may be be mixed with cervical mucus. Some women may experience mild lower abdominal pain or pelvic cramping similar to what they experience during menstruation. Note that women may bleed due to other causes, which won’t be covered here. So mid-cycle bleeding should not always be considered to be ovulation spotting.

Can You Get Pregnant Right after Your Period?

Yes, you can. But this depends on the length of your cycles and how long your period lasts. If you have a short cycle (say a cycle length of 22 days), it is possible that you ovulate just a few days after your period, i.e., if your menstruation lasts seven days. Given that sperm can survive in fertile cervical mucus for up to five days, you could get pregnant if you ovulate a little sooner than you expect.

Right after your period, your fertility is returning again. If you’re using fertility awareness techniques to identify ovulation, you will notice a change in the consistency of your cervical mucus, which becomes stretchy, clear and sticky. This is an indication that you’re approaching ovulation and you might get pregnant if you have sex. 

Although an egg has not yet been released from your ovary, you can get pregnant if you have sex during this phase. If you can have your partner’s swimmers waiting in your uterus, fertilization can occur once your body releases an egg. You can also improve your chances by having sex every other day.  

Can You Get Pregnant During Ovulation?

Of course! This is the ideal time for conception. If you don’t know when you ovulate, you can use tools such as a basal body thermometer or ovulation predictor to help you determine when you ovulate. You can also study the consistency of your cervical mucus or use the calendar method to have an idea of when you ovulate. 

If you know when you ovulate, you can time intercourse and consequently boost your conception chances. In general, your odds of conceiving are high if you have intercourse within 36 hours. Remember that once released, your egg cannot live beyond 12 hours.  

Can You Get Pregnant after Ovulation?

This phase of the menstrual cycle lasts approximately 12 to 16 days (for women with an average cycle length of 28 to 30 days). Your cervical mucus will no longer be slippery or look like egg white; it will be creamy and thick. The mucus will act as a barrier, preventing sperm from swimming up to the uterus. 

Since ovulation must have occurred anywhere between day 11 and day 21, your odds of conceiving during this phase are low. After egg release, your egg will die after 12 to 24 hours if fertilization doesn’t occur. So, if you know when ovulation occurred and you had sex ≥ 36 hours later, you’re unlikely to have your partner’s swimmers meet your egg. 

It is definitely not the best time if you’re planning sex for conception. But it can certainly be a good time to have fun with your partner if you’re in the mood. 


Given a couple’s low probability of getting pregnant naturally during a cycle, you can efficiently shorten your time to pregnancy by timing intercourse on days that you are most likely to conceive. Thanks to technology, you now have all the tools to help you identify your fertile window


I’m Princila, founder of Check Ovulation and a proud mom of two. I’m an alumna of James Lind Institute. After working in clinical jobs, my passion for writing took its toll, and I ended up switching careers to work in the medical publishing industry. I also have a passion for healthy food, which prompted me to take several online courses in nutrition and health offered by Wageningen University. (I still haven’t completed the courses thanks to my busy mommy schedule!). When I’m not writing/editing scientific and medical manuscripts or taking care of my family, I use my free time to research, learn, and write about healthy living. I have also authored a few books in the self-help niche using the pen names Princila Murrell or PN Murray. Protection Status