When (and What) Is a Fertile Window? [TTC + TTA Planning]

Whether you are trying to plan or prevent a pregnancy, having an understanding of how conception within the fertile window works will help you either get pregnant faster or be more effective at preventing an unplanned pregnancy.

In this article, we’ll cover everything you need to know about what the fertile window is, how long it lasts, and what’s going on inside your body during this time. We’ll also cover how to plan for your fertile window depending on your family planning goals, and the best tracking tools for accurately predicting your fertile window each cycle.

What is the fertile window?

The average menstrual cycle lasts anywhere between 21 to 35 days, and towards the middle of each cycle, there exists a period of time where it is possible to get pregnant. This time frame is known as the “fertile window”, and it includes the days leading up to ovulation and the day of ovulation.

The primary hormones at play during the fertile window include estrogen and luteinizing hormone (LH).

How long is your fertile window?

On average, the fertile window lasts for six days and occurs around mid-cycle. However, this may vary slightly among individuals.

What happens to your body during your fertile window?

Within the three to five days leading up to ovulation, estrogen (E2) levels begin to rise. This is caused by a dominant follicle in your ovaries, which will eventually release an egg during ovulation.

As your E2 levels rise, this then triggers the body’s production of luteinizing hormone (LH). This is known as the LH surge, and it helps the follicle release an egg into the fallopian tubes for fertilization.

Once an egg has been released through ovulation, it is possible to become pregnant. It’s important to note that sperm can live in the body for up to five days and an egg can only live for 24 hours. This is why the fertile window lasts six days - five days to account for the life of the sperm and one day to account for the life of the egg.

It is also normal to experience noticeable physical symptoms during this time as estrogen and LH levels rise. The most common symptoms around the time of ovulation include:

• Changes in cervical mucus and cervical positioning
• Changes in basal body temperature
• Increased libido
• Spotting, tickling, and/or pain in one of the ovaries

For more on what to expect around the time of ovulation, check out our article Ovulation Symptoms: 5 Signs of Ovulation.

Planning for your fertile window

What you choose to do during your fertile window will depend on whether or not you are actively trying to conceive or avoid pregnancy - here’s a brief look at what to do in both scenarios.

What to do if you’re TTC

If you are trying to conceive (TTC), you should try to have sex with your partner either every other day or daily during your fertile window. This will maximize the chance that you will conceive.

In general, if you are TTC, it’s also important to make sure that you are making healthy lifestyle choices. According to Harvard Medical School, women trying to get pregnant should avoid tobacco products, nicotine, marijuana, cocaine, and steroids. They should also aim to reduce stress, eat a well-balanced diet, and stay active through “restorative and aerobic” activities such as walking, yoga, and/or swimming.

For more pre pregnancy workout ideas, check out our article 5 Pre Pregnancy Workouts: How to Prepare Your Body when TTC.

What to do if you’re TTA

If you are trying to avoid pregnancy (TTA), you should avoid having sex with your partner during the six days of your fertile window. If you are not quite sure about the accuracy of your fertile window (perhaps you just started tracking or maybe your cycles are irregular), it’s also a good idea to abstain a day or two before and after your fertile window - just to be safe.

Even though there are prevention methods available such as condoms, it’s important to note that they are not always 100% effective at preventing pregnancy.

How can you calculate (or track) your fertile window?

No matter what your fertility goals are, keeping track of your fertile window is paramount to effective family planning. In addition to staying aware of the common symptoms associated with the fertile window, it is also possible to calculate it based on your average cycle length and the start date of your period.

Here’s a brief look at some of the best fertile window calculators that you can use at home.

Fertile window calculators

The Office on Women’s Health Website

One of the most straightforward options for calculating your fertile window is the ovulation calculator found on the Office on Women’s Health website.

To use this calculator, all you have to do is enter the start date of your last period and then indicate the length of your average cycle. The calculator then displays a calendar with your next estimated fertile window and day of ovulation. You can use this information each cycle to plan or avoid intercourse depending on your family planning goals.

The main benefit of this calendar is its simplicity. It’s simple to use and understand, and it gives you a clear, easy to read estimate of when your fertile window is likely to take place - not to mention it’s completely free. However, because it is just a calculator on a website, it cannot track your personal cycle patterns or symptoms over time.

The Clue App

If you are looking for something a bit more personalized, the Clue App is a wonderful period/fertility tracker app that has both a free and a paid version.

When using the free version, the app can give you an estimation of when your fertile window will occur. It can also predict when your next period should be. Additionally, you can use the app to track over 30 different elements of your cycle such as your mood, cervical mucus, and any pain/cramping. The paid version provides you with even more advanced features, such as six months’ worth of period/fertility predictions instead of three months, and a more in-depth analysis of your recurring symptoms.

The best thing about this app is that each time you track your period and symptoms, Clue learns more about your cycle and is able to offer more accurate predictions over time. The main downside however is that you cannot test or track your actual hormone patterns, which is one of the most reliable and accurate ways of predicting your period and fertile window.

The Mira App

The Mira App is another excellent tool for tracking your fertile window.

Even if you are not ready to invest in a Mira Analyzer just yet, the free app allows you to keep track of your period along with other physical symptoms. In addition to symptoms like cramping, headache, and acne, you can also track fertility-specific symptoms such as your sex drive, cervical mucus consistency, and mood. The app will then track your symptoms alongside your period, and give you an estimate of when your next fertile window will be.

Unlike Clue, Mira has the capabilities to test and track your exact hormone levels directly. For example, you may wish to use the calendar for a few months to get to know your cycle better, and when you are ready to get serious about planning a pregnancy, you can purchase the Mira analyzer and wands to use alongside the app. This allows you to test and track your estrogen (E3G), luteinizing hormone (LH), and progesterone (PdG) levels in urine. The app can then provide you with even more accurate predictions about your fertile window.

Fertile window FAQs