How to calculate your fertile days?

Whether you're trying to conceive (and even if you're not!), it's important to recognize your fertile days. In this blog post, we'll discuss how to recognize ovulation and the methods that can help.

Calculating your ovulation – 3 methods:

There are several methods to know when you ovulate: the calendar method, the cervical mucus method, and the basal body temperature method.

The first method is useful for getting an idea of ​​your cycle, but it's not precise enough. We'll discuss it briefly, though, because it can be an interesting starting point without requiring too much effort.

1: the calendar method

The calendar method is the easiest, but not the most reliable, way to get insight into your ovulation.

It's the old-fashioned pen-and-paper method: mark the first day of your period each month on a calendar (or use an app). The number of days between the first day of your period and the start of the next is the length of your menstrual cycle.

Your cycle length can vary each month, but it should always be roughly the same. If you have irregular periods, this method won't work well.

Once you know when your period starts, you can roughly calculate when you ovulate. Between 12 and 14 days after your period, you ovulate monthly. What's always certain is that the period between ovulation and the start of your period (the premenstrual phase) is always 14 days. This is due to the breakdown of the corpus luteum, a process that occurs predictably after ovulation. After the egg is released, the corpus luteum forms, which produces progesterone. This hormone prepares the uterine lining for a possible implantation of a fertilized egg.

If fertilization doesn't occur, the corpus luteum stops producing progesterone after about 14 days and dies. This leads to the shedding of the uterine lining, or menstruation. This ensures that the luteal phase always has a relatively fixed length, usually between 14 and 16 days. What is variable is the number of days before ovulation (the follicular phase). This can vary between individuals and is responsible for some women having a longer or shorter cycle than the standard 28 days.

Your fertile window is the five days before ovulation, the day of ovulation itself, and the day after ovulation. So, about a week in total.

There are many apps like Clue or Flo that simplify the old-fashioned calendar method. Keep in mind, however, that these apps rely solely on algorithms. They only consider the length of your period and don't track other important signals (your basal temperature and cervical mucus, see below).

2: the cervical mucus method

Want to know exactly when you're ovulating? Then look at your cervical mucus.

Your hormones change throughout your cycle, and one of the things that affects your hormones is the amount and feel of vaginal mucus (also known as cervical mucus, cervical mucus, or discharge).

If you feel and look at your vaginal mucus every day and write down what you see, you can learn a lot from it.

When you're ovulating , your mucus is thick, wet, and slippery. It looks a bit like raw egg white or a runny nose. 🙂 If your cervical mucus looks like this, you're in your most fertile period. This is the best time to try for a baby.

Try tracking your mucus throughout your cycle and see how it changes throughout the month. It can be difficult at first to know what to look for, but eventually you'll recognize patterns. Read more about this in our blog . 

3: Using the Basal Body Temperature Method

This method is a little more complicated (the word alone is simple: ba-sa-le), but in combination with the cervical mucus method, this is the ultimate way to calculate your fertile days.

Your basal body temperature (BBT) is your body temperature when you're completely at rest. To track ovulation using your BBT, take your temperature every morning as soon as you wake up (before you even get out of bed!).

You'll need a special thermometer for this: a basal thermometer. This is a more sensitive version of a regular thermometer. This thermometer uses two zeros after the decimal point.

This is important because your basal body temperature rises by half a degree when you ovulate. So, if you carefully track your basal body temperature, you'll notice a temperature increase just before ovulation.

You can track your temperature daily on a piece of paper, or use an app like Natural Cycles . This is the app Guud Woman founder Morgane uses. There are also all sorts of handy devices available these days, such as the Oura ring and Whoop, that track your temperature. You can then link these to Natural Cycles, so you don't have to take your temperature yourself. The Oura ring collects "temperature trend" data while you sleep, rather than a single reading. It's not a BBT (basal body temperature). The Natural Cycles algorithm then creates an "absolute value" based on that temperature trend data, and that's the reading you'll see in the Natural Cycles app.

Note that this method of tracking your temperature alone isn't ideal if you're trying to conceive. As soon as you see a rise in temperature, you've already ovulated and may be too late. Use this method primarily to track your entire cycle and fertile window.

When should you have sex to get pregnant?

We'd love to start by telling you how wonderful it can be to have sex every day, and that enjoying it is important. But at Guud Woman, we know better than anyone that getting pregnant can sometimes be quite unsexy.

For the best chance of pregnancy, you should have sex every day or every other day for the five days leading up to ovulation, the day of ovulation, and the day after. I personally always recommend having sex every other day for optimal sperm quality, and since you can still be a day past ovulation, I also recommend having sex for up to two days after your expected ovulation.

Doable, or does it sound like a lot? The good news is that you'll probably already have a higher sex drive. This is Mother Nature's clever way of helping the world reproduce!

Much is written about the "right" sex position to increase your chances of conception. But science shows that there's no specific sex position that increases the chance of pregnancy.

Some lubricants can negatively affect sperm and prevent them from reaching the egg. So make sure you use a fertility-friendly lubricant.

Want to know more about sex during your cycle? Here's how your cycle affects your sex drive .

What is the best way to calculate your ovulation?

The best way to track your cycle is a combination of checking your cervical mucus and tracking your basal body temperature.

You can do this using the Natural Cycles app, or learn how to do it yourself with the Sensiplan method. Sensiplan is a scientifically proven method that combines all your body signals with data. The idea behind Sensiplan is that when you are fully aware of your body and know your basal body temperature, cervical mucus, bleeding, and other symptoms, you can accurately plan or prevent pregnancy.

If you need help tracking your cycle, we recommend contacting a Sensiplan coach. More information about Sensiplan can be found here.

Hopefully, this blog has been helpful. Just a quick note to conclude. Why are we sometimes so cautious with our wording? Because we want you to understand that there's no magic pill that solves everything (unfortunately!). Supplements can help support your health, but other factors also play a role, such as genetics, sleep, exercise, and diet. Do you have questions about your specific situation? Chat with us – we're happy to help, with no obligation!