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Fertile Window and Signs of Ovulation

The information provided herein does not constitute an expert or medical advice, nor intended to replace such advice.

Women Health

​​​​​Whether you’re trying to conceive or trying to avoid pregnancy, it’s very useful to learn how to identify your fertile window. But what exactly is a woman’s fertile window?

Your possibility of getting pregnant isn’t exactly the same each day of the month. Your fertile window simply refers to the window of time when you are most likely to conceive.

Read on to learn more about your fertile window and how you can track it.

What is the fertile window?

The fertile window refers to the period of time in which you are ovulating and can naturally become pregnant via sexual intercourse. 

The average fertile window lasts approximately 5 to 7 days, although your chances of conceiving are likely much lower at both ends of the window. As you probably already know, your ovaries release one egg (sometimes, more than one) that can be fertilized each month.

Once you ovulate, the egg will only last 24 to 48 hours before it begins to deteriorate and is no longer viable.

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According to the Mayo Clinic, sperm cells can live inside your body for up to 5 days after ejaculation. That means that even if you don’t have sex on the exact day when you ovulate, sperm cells that are still alive from sex on previous days can fertilize the egg, resulting in pregnancy. 

The process that leads to ovulation is controlled by different hormones, such as estrogen and progesterone. These hormones send signals to your ovaries so that an egg can become fully matured to be released during ovulation.

This typically happens 14 days before your next period starts. So if your menstrual cycle is 28 days long, your ovulation will typically fall on day 14. But if your cycle is 35 days long, you will ovulate on day 21. Your fertile window will depend entirely on when you ovulate.

What are the signs of ovulation?

Each month, different hormones act on your body to stimulate your ovaries so that one egg can become fully mature and be released during ovulation. Your body will usually give you some signs when it’s getting ready to ovulate.

These signs may be more subtle for some women, and in some cases, you may not even notice them unless you’re looking for them. According to the NHS, signs of ovulation can include:

  • As you approach ovulation, your vaginal discharge will become clear, stretchy, and watery. These changes are meant to help sperm cells swim up your cervix and into the uterus to facilitate conception.
  • A small rise in body temperature, which is used in body basal temperature monitoring to identify your fertile days.
  • Some women experience spotting, breast tenderness, or light abdominal pain when they ovulate.

If you’re trying to conceive, the Mayo Clinic recommends to have sex right before you ovulate to ensure that sperm cells will already be waiting inside your uterus by the time the egg is released.

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And if, on the other hand, you’re trying to prevent pregnancy and rely on natural contraception, you should skip intercourse during your entire fertile window. Alternatively, you could also use an additional contraceptive method, such as condoms or a diaphragm, during these days.

How to track your fertile window

Your ability to accurately track your menstrual cycle will largely depend on how regular these cycles are. Some women have very irregular cycles, which can make it difficult to predict when your fertile window will occur during any given month. 

Ovulation tracker apps can be a good place to start. There are many different apps that you can download on your smartphone; these apps will ask you to log your period days and any symptoms that occur before, during, or after your period. They will then use this information to predict when your next period and fertile window will fall.

Home ovulation prediction tests can also be purchased at most drugstores. Similarly to home pregnancy tests, these tests simply require that you urinate on them. The best way to use these tests is to start testing a few before you’re expected to ovulate, and a positive result means that you’ll ovulate within 24 to 36 hours.

Keep in mind that these methods are most reliable for women who have very regular menstrual cycles, but they still have a higher failure rate when compared to other contraceptive methods, such as condoms and hormonal contraceptives. This happens because accurately predicting ovulation can be difficult, and not every woman has a regular menstrual cycle.

According to the NHS, it can take 3 to 6 months to get to know your cycle well enough to be able to predict your fertile window.

You should also remember that condoms are the only method that can keep you protected against sexually transmitted infections (STIs). 

Additionally, there are external factors that can affect ovulation and make it happen a few days earlier or later than usual, making your fertile window harder to predict.

According to a study published in the British Medical Journal, it’s impossible to predict a sporadic late ovulation — this study found that women have a minimum 10 percent possibility of getting pregnant on every day of the menstrual cycle between days 6 and 21.

Written by Dr. Andrea Pinto Lopez on June 29, 2021. 


Dr. Andrea Pinto Lopez

Dr. Andrea Pinto Lopez

Dec 11, 2022

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