When Are You Most Fertile?

Whether you’re trying to get pregnant or just seeking to better understand your body and menstrual cycle, it’s good to understand when you are most fertile.

This is both a simple and difficult question. On the one hand, there’s a very clear answer about when a woman is most likely to get pregnant. On the other, pregnancy and fertility is highly tied to each woman’s cycle and that can be highly individual to each woman, and even variable for every individual woman.

Understanding Your Cycle and Fertile Days

If you want to learn more about fertility, it really starts with understanding your entire menstrual cycle. Most women are acutely aware of their period (the first day of your period is the first day of your cycle), but they may be less familiar with the other events in their entire menstrual cycle.

The first day of your menstrual cycle is counted from the first day of your period and ends at the beginning of your next period. The average cycle length is 28 days. Ovulation is a key event in your cycle and it occurs on approximately day 14 of an average 28-day menstrual cycle.

The Fertile Window: Take Note If You’re Trying to Get Pregnant

For those trying to get pregnant, knowing when you might be ovulating and identifying your fertile days is important. 

Your most fertile days (the “fertile window") are the 5 days leading up to and including ovulation. The fertile window is when you’re most likely to conceive and have the greatest chance of getting pregnant. 

So, having sexual intercourse during your fertile window (your most fertile days) gives you the best chance of ensuring the sperm is present when the egg is released so that you can successfully become pregnant.

It’s worth noting that many women do not have an average cycle length of 28 days. And even if they don't have irregular cycles, when you ovulate can be impacted by many factors, from stress and jet lag to smoking and illness. So, rather than thinking in terms of day X of your cycle, look for the ovulation symptoms described below to identify your fertile days.

What’s Age Got to Do With It?

Of course, fertility can be impacted by several factors. Lifestyle and health conditions can impact fertility; however, age is one of the biggest natural reasons fertility can be decreased.

Your odds of getting pregnant are highest in your 20s and 30s, as this is when women are technically the most fertile and have the highest quantity of quality eggs. 

After the age of 35, the chances of becoming pregnant begin to decline And by the time a woman turns 40, her chances of getting pregnant decrease to 10% per menstrual cycle.

Ovulation: What Is It?

During reproductive ages, the ovary releases an oocyte (immature egg) every month. Ovulation occurs when ovary follicles rupture and release the oocyte, which travels to the fallopian tube and becomes an ovum. 

The rupture of the ovary follicles can cause some light spotting and some can even feel it happen in their body. However, for the vast majority of women, the moment usually goes unnoticed.

After the oocyte is released from the ovary, it moves into the fallopian tube. At this point it is called an ovum. The egg stays in the fallopian tube for about 24 hours, waiting for a single sperm to fertilize it.

If the egg is not fertilized by sperm during that time (and pregnancy does not occur), it disintegrates (breaks down) and menstruation (your next period) begins 11–16 days later.

Signs of Ovulation in the Menstrual Cycle

Ovulation usually goes unnoticed in many, but there are some symptoms that most women can learn to track or pay attention to so you can keep an ovulation calendar. These include your basal body temperature, cervical mucus, and more...

Your Basal Body Temperature Falls

One of the most objective ovulation symptoms is that your basal body temperature drops a little bit just before your egg is released from your ovary. Then, 24 hours later, your basal temperature rises and stays up for several days.

If you're trying to get pregnant, it's advisable to take your temperature to understand when you're ovulating and when your fertile window is.

According to Healthlink BC, your basal body temperature averages between 36.1°C (97°F) and 36.4°C (97.5°F) before you ovulate. It averages 36.4°C (97.6°F) to 36.4°C (97.6°F) after you ovulate. 

Cervical Mucus Changes When You Ovulate

The changes in your cervical mucus over the course of your menstrual cycle also hold clues about when your ovulation window might be.

If your cervical mucus is...

• Dry or sticky: It’s unlikely you’re ovulating
• Creamy cervical mucus: Ovulation may be coming
• Wet or watery: Ovulation may start soon
• Wet and stretchy (eggy white texture): You may be at your day of ovulation

Your Cervix Softens and Opens Up

As you approach your most fertile time, your cervix softens. This is sometimes known as having a short, high, open, and wet cervix (SHOW). 

For a step-by-step guide to checking your cervix position, visit this guide on Flo’s website. 

You May Experience Slight Twinge or Cramping

Mittelschmerz translates literally as “middle pain” and is the name for the slight twinge or cramp that some women experience when the follicle releases the egg on the day of ovulation during their menstrual cycle.

For many women, there is no sensation whatsoever. 

According to the Mayo Clinic “Mittelschmerz pain occurs on the side of the ovary that's releasing an egg (ovulating). The pain may switch sides every other month, or you may feel pain on the same side for several months.”

Some Light Spotting May Occur When You Ovulate

When the ovaries release the oocyte, a tiny follicle ruptures to allow it to be released. Ovulation can be a cause of spotting for a day or so.

For some women, spotting that occurs around the time of ovulation is light red or pink in color. This is because we also produce more cervical fluid around the time of ovulation and the blood gets mixed with that fluid, causing it to be a lighter shade.

Increased Libido or Sex Drive

The most well-known sign of ovulation is an increased sex drive. It’s important to know that this does not mean you’ll only want to have sexual intercourse during ovulation and your fertile window. But it may definitely mean that you may experience an increased libido when ovulation occurs.

According to a report on Psychology Today, "ovulating women do clearly increase their sexual desire, and they do increase the frequency with which they have (sexual intercourse) with their current partners.”

How Long Do You Ovulate For?

Ovulation lasts between 12 and 24 hours. That's how long the egg released by the ovary is viable for fertilization. Tracking ovulation is helpful in identifying your fertile days. 

How to Know Your Fertile Window: Ovulation Predictor Kits

In addition to tracking the signs of ovulation listed above, there’s another step you can take to predict your fertile days: Ovulation tracking. 

Using an ovulation calculator is especially helpful for those who want to increase their chance of getting pregnant by helping identify the fertile window and ovulation day.

An ovulation predictor kit (also sometimes called an OPK) is a test that detects the presence and concentration of luteinizing hormone (LH) in your urine. Between 12–48 hours on average before ovulation, there is a brief surge in luteinizing hormone levels, which helps you identify your fertile time. 

Ovulation predictor kits may be especially helpful for women who want to have the best chance of pregnancy by identifying their fertile days and ovulation window. 

You'll know if pregnancy has occurred by administering a pregnancy test. Or if your next period doesn't come when it's due according to your period calculator.

If you're planning to get pregnant, it's always worth seeking professional medical advice from a doctor or fertility specialist to ensure you and your partner understand your reproductive health and are setting yourselves up for success.

Written by Jane Flanagan — Updated on April 5, 2022.

We hope you found this post informative — but remember: we’re not doctors and this post is not medical advice! While all posts are fact-checked and well researched, we always recommend you chat with your doctor about any questions or concerns you might have regarding a medical condition. We’re here to support and educate, but never with the aim of disregarding professional medical advice you’ve been given. Phew, now that that’s out of the way, you can go on living unapologetically free.